Why is WinSCP so slow?

I'm only getting a transfer rate of 1500KB/s from my Linux server to my Windows computer. The windows computer is running Linux and Windows as dual boot, when I scp from Linux to Linux I get ~8MB/s transfer rate without compression enabled.
I checked WinSCP options and compression is off, I just downloaded the latest version 4.0.5 and it is the same problem.
I need to transfer 25GB from Linux to Windows and WinSCP estimates 4.3 hours, I can burn the files to DVD faster then that....

Any ideas on what is causing this?

Please read FAQ first.

I noticed it the other day and had to come back to finalize this post. For some reason WinSCP defaults to SFTP as the transfer protocol. I assumed it would use SCP by default due to the software's name .... switched it SCP now the speeds are excellent. I hope this post gets indexed into Google because the FAQ is not but another post without solution is.

Hope this helps somebody else.

BTW, instead of posting: "Please read FAQ first." You could have posted "Switch to SCP" would have been nicer and more helpful.

Sadly, for me, switching between SCP and SFTP makes absolutely no difference. It feels like a software cap, but obviously isn't. Nothing in the FAQ makes any difference.

Strangely, bringing the "5%-100%" slider down to 5% only cuts the performance in half.

Sadly, for me, switching between SCP and SFTP makes absolutely no difference. It feels like a software cap, but obviously isn't. Nothing in the FAQ makes any difference.

Have you tried PSFTP or PSCP?

This issue has been added to tracker.

I had 6Gb to download and noticed the same thing, In the middle of the download I ran windows update and to my suprise while the update was running the transfer rate increased by 5 fold, when the update was finished the transfer rate went back to slow. I then ran some high CPU tasks and what do you know, the transfer went up each time the Task were running, and went back to slow when they finished.

Guest wrote:

I had 6Gb to download and noticed the same thing, In the middle of the download I ran windows update and to my suprise while the update was running the transfer rate increased by 5 fold, when the update was finished the transfer rate went back to slow. I then ran some high CPU tasks and what do you know, the transfer went up each time the Task were running, and went back to slow when they finished.

What protocol are you using?

SFTP

Guest wrote:

SFTP

Thanks. What version of WinSCP are you using? Can you try 4.1 beta, if you do not use it already?

Anonymous wrote:

Strangely, bringing the "5%-100%" slider down to 5% only cuts the performance in half.

What is this speed slider? I have seen reference to it but have downloaded 4.1.2 (among other versions) and can't find it.

diamondboy wrote:

What is this speed slider? I have seen reference to it but have downloaded 4.1.2 (among other versions) and can't find it.

The slider has been replaced with input box in 4.1.

After spending a decent amount of time trying to fix up Windows XP networking to run quicker I stumbled onto another program- Tunnelier. Transfer rates are MUCH quicker using Tunnelier rather than WinSCP.

Monitoring throughput on the TCP stack using 'Bandwidth Monitor' utility:
WinSCP sustains an average of 1.8mbps
Tunnelier sustains an average of 4mbps

If you compare the file transfer rates as reported inside each client:
WinSCP sustains an average of 160KiBps
Tunnelier sustains an average of 500kBps

Those tests are done using SFTP and no compression. It is trickier to compare once you turn on compression because the numbers bounce around too much in WinSCP- it does not do a good job of SMOOTHING out the average transfer rate that it displays.

The way WinSCP was pegging at 1.8mbps I thought something in the OS networking stack was preventing it from transferring quicker- but it must not be the case if another client can fly beyond that limit without any trouble. Also WinSCP was using Blowfish cipher (as recommended for better throughput). There was not any noticeable difference when switching between the different ciphers in Tunnelier (in fact in those tests Tunnelier was using AES-256).

Well I do like the WinSCP application a lot- which is why I wanted to share. Hopefully this will provide some motivation that the transfer rates need to be improved. WinSCP is just not fast enough when you need to do large transfers (I am talking about >100GB). In that case we are talking a DIFFERENCE of several DAYS).

-Steve

I too verified that there is a speed problem, transferring a file with size 74,319,711, was going to 2 to 3 minutes (local lan, gigabit network)
I installed bitvise tunnelier(as suggested earlier), wow....what a speed difference.

vista(32bit, sp1)
scp 4.0.7

This speed difference is astonishing. But as Tunnelier can be downloaded for free the WinSCP autor should be able to verify the difference by himself now.

I must say that this difference is quite important, not only for big files. In many parts of the world internet is slooooow. FTP is just on the edge of being usable. If you turn to SFTP it becomes unusable (due to the added overhead and the many additional requests, it seems). That simple. Travel to some countries in Asia and you know what I mean. More timeouts than transfer. But when it doesn't work with WinSCP, it does work with Tunnelier. So this really should be fixed...

So, can we expect a fix?

Anonymous wrote:

I noticed it the other day and had to come back to finalize this post. For some reason WinSCP defaults to SFTP as the transfer protocol. I assumed it would use SCP by default due to the software's name .... switched it SCP now the speeds are excellent. I hope this post gets indexed into Google because the FAQ is not but another post without solution is.

Hope this helps somebody else.

BTW, instead of posting: "Please read FAQ first." You could have posted "Switch to SCP" would have been nicer and more helpful.

Thank you! Works for me! Looks like SFTP is slow as turtle. Maximum speed is about 1.5Mb/s, no matter what CPU you have. After switching to SCP, transfer rate and CPU usage climbed up. After trying different encryption modes i got it running about 5.5Mb/s.

(As side note, Linux <-> Linux SCP transfers are much faster with same hardware)

Hi,

i had the same problem. Using SCP is faster than using SFTP but now i use cygwin & openssh at command-line.
This is 3x faster than WinSCP with ssh-protocoll.
Something is slowing down WinSCP.

Maybe you find it someday.

Must say I've ALWAYS had this problem with WinSCP. it's about 10x slower than scp on the same hardware :(

I very rarely use windows, mainly guests that come to my house, and I want to copy large amounts of data across to their windows boxes.

Any suggestions? I'll try Tunnelier, but I really want LAN speeds like I get linux to linux (sustained 11MB/s using scp). i.e. I want the data to stream into windows at 10MB/s, not 1MB/s..

I haven't tried turning off SFTP, will try that next time a windows box walks into my living room, but

It's unfortunate, as WinSCP is a great bit of software apart from failing at this critical thing.

Sorry this is a bit more of a "me too" rant than a useful support request.

Craig

Just an update. I tried Tunnelier. Very impressed! And it ran at 8.5MB/s (on 100Mb ethernet), about 8.5x as fast as WinSCP was on the same Vista laptop.

i can confirm this. tunnelier is "much" faster.

the question is, why?

currenly i am "forced" to use tunnelier but i would really like winscp to catch up, as tunnelier is bloated and lacks usability.

When connecting (or edit the saved session) use the SCP protocol. With it the transfer changed from 1.8 - 2.2Mb to 8.5 - 8.8Mb with 100Mb lan.

VERY SLOW but nice GUI

had .3 to 2.5 MBs where copy from the commandline with SCP gets 8.5MBs

if you run wireshark you see why: many tiny packets, ACKs etc

think the problem is fragmentation: there are many 1400 odd size packets, immediately followed by another few hundred, and the latency then ruins high transfer rates

guess one would have to compensate for the "growth" of packets due to encryption - maybe with some change to the MTU generated by WINSCP (e.g. smaller size max 1300 byte?)

nm23728 wrote:

guess one would have to compensate for the "growth" of packets due to encryption - maybe with some change to the MTU generated by WINSCP (e.g. smaller size max 1300 byte?)

I hope this gets better with 4.2.x. If not let me know then.

Something I have noticed when running WinSCP to a USB hd ... it does an awful lot of head movements during copy ... I just copied a file using Samba, which was about 3-4x as fast, while I could hardly hear the drive doing anything. Doe the same thing with WinSCP, and the head seems to be moving dozens of times every single second ... and no, the drive isn't very fragmented, either ... (that's why I tried the Samba copy, too)

Seems to me WinSCP has some problems with its I/O handling ...

GarryG wrote:

Something I have noticed when running WinSCP to a USB hd ... it does an awful lot of head movements during copy ... I just copied a file using Samba, which was about 3-4x as fast, while I could hardly hear the drive doing anything. Doe the same thing with WinSCP, and the head seems to be moving dozens of times every single second ... and no, the drive isn't very fragmented, either ... (that's why I tried the Samba copy, too)

Thanks. What protocol have you used? Was it upload or download? (if that matters).

Tried both sftp and scp ... in fact, in contrast to some reports here scp was actually slower than sftp ... (1.5M / .8M). Copying via scp from linux to linux resulted in 5M, so the line (STM1) as well as the source server were fast enough ... transfer was download from the server ...

Tried tunnelier, and got around 8-10M/s ... (!)

FileZilla (SFTP): ~1.1 MB/s (unknown)
WinSCP (SFTP): ~300 kb/s (aes)
WinSCP (SCP): ~800 kb/s (blowfish)
Cygwin/OpenSSH 5.0p1 (SCP): ~1 MB/s (aes128)

Btw, my bandwidth over cable is about 2.2 MB/s (which I get when transferring over HTTP).

If you look at the debug output of scp (cygwin), they set some socket options and make TCP adjustments:
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug2: channel 0: rcvd adjust 2097152
debug2: channel 0: rcvd ext data 44
Sending file modes: C0644 52428800 testfile
window 1998780 sent adjust 98372
debug2: channel 0: window 1982464 sent adjust 114688
...

I don't know if WinSCP does that, but if not, that would explain the performance loss.

mb wrote:

If you look at the debug output of scp (cygwin), they set some socket options and make TCP adjustments:
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug2: channel 0: rcvd adjust 2097152
debug2: channel 0: rcvd ext data 44
Sending file modes: C0644 52428800 testfile
window 1998780 sent adjust 98372
debug2: channel 0: window 1982464 sent adjust 114688

WinSCP does more or less the same.

I have an 800mg file on Unix that I was attempting to transfer via WinSCP to Windows.
SFTP = 470kbps
SCP = 1400kbps

so I ended up using Filezilla at SFTP = 4.4mbps.

Still using WinSCP because of some of the extra features ie. command buttons etc. but Filezilla is catching up, esp when it comes to the file transfer speed.

I tried t ouse winscp to copy files over to my virtual machine (Host Win XP/guest debian 5) over ms loopback interface....
Authentication takes ages, the transfer starts slowly enough to time out
(odd thing: when transfer finally picks up you can see it on the progress bar ... below the dialog with the ignore/abort choice - dialog should vanish in this moment, shouldn't it?)

To sum up the transfer is very uneven up to 3 mb/s at moments, often stalls.
Cygwin's scp 15MB/s steady.

SCP 4.2.6 build 721

Regards,
Maciej

If i am not mistaken, WinSCP's SFTP/SCP code is based upon PuTTY's code which has had this performance bug for ages now. Actually all applications that use the code from PuTTY have this issue. :(

Hi,

I need to connect to sql server database from winscp.com , is there a way . I could find call statement is present. BUt i donr know hoe to connect to database to get some information from tables .

actaually i am getting information from text file .

open user:password@example.com
cd home/asuser
get *.txt D:\max\

Instead of getting info from file , i am planning to store these info in sql server tables and get the info from tables to this winscp.com.

please let me know if you find any way along wth the example

Thanks
Raghav

Tested version 4.27 versus Filezilla 3.2.7.1 and got near-as-dammit same transfer speeds to a local box over wireless ethernet (SFTP or SCP made no difference in WinSCP, Filezilla only support SFTP).

BarrySmoke wrote:

I too verified that there is a speed problem, transferring a file with size 74,319,711, was going to 2 to 3 minutes (local lan, gigabit network)
I installed bitvise tunnelier(as suggested earlier), wow....what a speed difference.

vista(32bit, sp1)
scp 4.0.7

Tunnelier is so much faster than Winscp (3x) with same hardware, same network, same copy job...

Hi,

has anything happend regarding speed lately? I just installed the latest version (4.3.5). Downloads are still so slow that WinSCP is hardly usable for more than a couple of files. FileZilla has other issues, but is super fast in comparison. Of course I read the FAQ and most of the rest of this thread. Didn't help.

Cheers, Ralf.

lausianne wrote:

has anything happend regarding speed lately? I just installed the latest version (4.3.5). Downloads are still so slow that WinSCP is hardly usable for more than a couple of files. FileZilla has other issues, but is super fast in comparison. Of course I read the FAQ and most of the rest of this thread. Didn't help.

Please try 5.0.x beta. It has this fix included:
https://winscp.net/tracker/690

For me there was only a marginal speed improvement with using SCP instead of SFTP both using AES transfer protocal. I got a big speed boost however by changing the tranfer protocal to blowfish. It was slightly more than 2x speed improvement form 1360 KiB/s to 3100 KiB/s.

lausianne wrote:

Hi,

has anything happend regarding speed lately? I just installed the latest version (4.3.5). Downloads are still so slow that WinSCP is hardly usable for more than a couple of files. FileZilla has other issues, but is super fast in comparison. Of course I read the FAQ and most of the rest of this thread. Didn't help.

Cheers, Ralf.

At least--and I'm searching for the good here---WINSCP has this great feature to shut down the computer when it's done. That's a good thing.

don't forget to check if your firewall cause the slow speed. i also had speed problems and partly my firewall cause the loss of speed.

consistency wrote:

don't forget to check if your firewall cause the slow speed. i also had speed problems and partly my firewall cause the loss of speed.

How do I check for this? And if found, how do I correct this?

Hi!

I have the same problem. I used WinScp 4.2.x and upgraded to the latest version 4.3.5. Here are results when coping to a server with bandwidth 10MBit/s:
scp.exe from git installation: 1.1+ MByte/s
ncftp (ftp protocol): 400 kByte/s
Filezilla (ftp): 1.1+ MByte/s
Filezilla (sftp): 1.1+ MByte/s
WinScp with scp protocol: 50 kByte/s
WinScp with ftp (no encryption) protocol: 200 kByte/s

PC used: Intel Core i7 2600 / 3.4 GHz. Can encrypt a lot more than 1 MB/s
All test are done in the same time, from the same pc, to the same remote server.

So if scp from mingw/git installation can copy with full speed, why WinScp can't? WinScp is 2 times slower than slowest scp/ftp client

Edit: WinScp 5.0.5 reaches 470 kb/s with scp and about the same speed with ftp. Maybe it's good to make these buffers editable or download source of openssh scp client and see what's the buffer size in it.

Freitag wrote:

consistency wrote:

don't forget to check if your firewall cause the slow speed. i also had speed problems and partly my firewall cause the loss of speed.

How do I check for this? And if found, how do I correct this?

its not only firewall, its also antirus software, often they come with a firewall build in.

to check for it is to look at your system tray if any firewall or antivirus software icon is located there and into your "installed software" section and search for it.

what to do after you found it:
if you are in a safe environment (no internet connection, additional hardware firewall) you can try to disable / deinstall your security software (check if you have a installable version allready downloaded / on your harddisk before deinstalling!). then reboot and make all the speed tests again. also in some security software you can configure how much is filtered/monitored. so you can disable some realttime scanning stuff but keep the rest of the software active.

but i would never use a pc without antivirus / firewall softeware, i pay the price of extra security with a slower network speed.

best speed i got with linux to linux unencrypted file transfere without firewall
windows7x64 was slower in general (don't know why)
my firewall <invalid hyperlink removed by admin> / <invalid hyperlink removed by admin> which i think is a great software if you want to have detailed control over your programs, reduced my transfere speed a lot (can't remember the exact numbers)
in combination with winscp the speed is quite slow (have not tried the protocol switch to scp and the change of the encryption algorithm).

i live with the slow speed, because for me security is more important than speed.

if you have speed problems and can determine that the firewall is the reason for it, you also can contact the software company who made the firewall and tell them what tests you made and that your are not pleased with the result.

still it's not normal openssh's scp and filezilla to be faster on the same conditions

Can I ask all people posting here to mention version of WinSCP they are using? Thanks.

martin wrote:

Can I ask all people posting here to mention version of WinSCP they are using? Thanks.

WinSCP version:
5.0.5 Build 1782

While doing FTP synchronization remote local docs / remote docs

While in the GUI or running from script, receiving file transfer speeds from
10KB-500KB but averages around 100KB-300KB,
I can run other utilities and they transfer at 5MB+

FTP is the only protocal that can be used but it is definately being limited in WinSCP somewhere.

On another note. I do get many timeouts when doing a compare before the synchronization starts transfering files... causing it to timeout. Is there a way for the compare to continue on reconnect as do file transfers?

Would this work help lead to a faster implementation?

https://www.psc.edu/hpn-ssh-home/hpn-ssh-faq/

martin wrote:

Can I ask all people posting here to mention version of WinSCP they are using? Thanks.

Just wanted to chime in with my experiences with this issue..

Currently using 5.0.5 Build 1782 and not having speed issues, able to upload at my connection's max rate (~500 KB/s). However 4.3.5 and 4.3.6 were being mysteriously being capped at about 50 KB/s for some reason; I had all limiters that I could find disabled.

Another wrinkle to the story is this machine had its hard drive replaced on 12/26/11 with a fresh OS install. The previous HD/OS install with WinSCP 4.3.5 didn't have the above issue, however WinSCP was originally installed with 4.2.8 or 4.2.9 (going by WinSCP release dates and remembering when I RMA'ed the HD).

Anonymous Coward wrote:

Would this work help lead to a faster implementation?

https://www.psc.edu/hpn-ssh-home/hpn-ssh-faq/

It's implemented already:
https://winscp.net/tracker/17
https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/flow-control-filexfer.html

dcmorton wrote:

Currently using 5.0.5 Build 1782 and not having speed issues, able to upload at my connection's max rate (~500 KB/s). However 4.3.5 and 4.3.6 were being mysteriously being capped at about 50 KB/s for some reason; I had all limiters that I could find disabled.

Likely due to this change:
https://winscp.net/tracker/690

Thanks for sharing your (positive) experience.

dcmorton wrote:

Currently using 5.0.5 Build 1782 and not having speed issues... <<snip>>

I can confirm that 5.0.5 build 1782 has solved my speed issues as well (and quite nicely, at that). My SFTP uploads have traditionally struggled to hit 400 Kbps on a very large pipe, and now they easily reach 9 Mbps. Thanks so much!

mjt772 wrote:

I can confirm that 5.0.5 build 1782 has solved my speed issues as well (and quite nicely, at that). My SFTP uploads have traditionally struggled to hit 400 Kbps on a very large pipe, and now they easily reach 9 Mbps. Thanks so much!

Thanks a lot for feedback!

what is the max speed that is possible? i am on gigabit internally and i can manage 9.1MiB with sftp to my server. running the newest beta 5.0.5.
thanks

martin wrote:

mjt772 wrote:

I can confirm that 5.0.5 build 1782 has solved my speed issues as well (and quite nicely, at that). My SFTP uploads have traditionally struggled to hit 400 Kbps on a very large pipe, and now they easily reach 9 Mbps. Thanks so much!

Thanks a lot for feedback!

I use WinSCP(sftp) as the transport agent within my file ingest framework. Would you consider 5.0.5-beta production ready? Stable enough?

The increased throughput in this version is significantly greater than the throughput seen with current stable(4.x) branch.

TBANKS wrote:

I use WinSCP(sftp) as the transport agent within my file ingest framework. Would you consider 5.0.5-beta production ready? Stable enough?

It is reasonably stable. Though not as stable as 4.3.x yet.

martin wrote:

TBANKS wrote:

I use WinSCP(sftp) as the transport agent within my file ingest framework. Would you consider 5.0.5-beta production ready? Stable enough?

It is reasonably stable. Though not as stable as 4.3.x yet.

"reasonably stable" enough to introduce into a production environment?


thanks for your response.

martin wrote:

TBANKS wrote:

I use WinSCP(sftp) as the transport agent within my file ingest framework. Would you consider 5.0.5-beta production ready? Stable enough?

It is reasonably stable. Though not as stable as 4.3.x yet.

Lastly.. why was the increased buffer size pulled from the 4.3 branch?

I am leaning towards using the 5.x beta version within production, but the retraction of the buffer code has me a bit worried.

Please advise.

TBANKS wrote:

"reasonably stable" enough to introduce into a production environment?

Hope so. Just test it and you'll see for yourself.

TBANKS wrote:

Lastly.. why was the increased buffer size pulled from the 4.3 branch?

I am leaning towards using the 5.x beta version within production, but the retraction of the buffer code has me a bit worried.

For very few users with the increased buffer size, WinSCP stopped working altogether. Likely due to network misconfiguration on their side. As 4.3.x GUI is frozen, I could not add configurable option to disable the increase, so I pulled it.

I must admit 5.0.5 was fastest version I ever used. 5.0.6 is slower and 5.0.7 is as slow as 4.x for me. Working on 100Mbit LAN, in SCP mode with Blowfish encryption I am getting <500kb/s :( 5.0.5 was 2-3 times faster.

tjwasiak wrote:

I must admit 5.0.5 was fastest version I ever used. 5.0.6 is slower and 5.0.7 is as slow as 4.x for me. Working on 100Mbit LAN, in SCP mode with Blowfish encryption I am getting <500kb/s :( 5.0.5 was 2-3 times faster.

There's handly any change between 5.0.5 and 5.0.7 that might cause this. Except for Blowfish being default in 5.0.7, but that should actually increase speed. Can you email me a log files from 5.0.5 and 5.0.7?

I also noticed that 5.0.7 is much slower, with blowfish I can achieve only around 4MB/s max, with AES I'm getting 10MB/s on 100Mbit network, but cpu usage is very high. Is winscp using AES-NI instruction set on cpus which support them?

doug wrote:

I also noticed that 5.0.7 is much slower, with blowfish I can achieve only around 4MB/s max, with AES I'm getting 10MB/s on 100Mbit network, but cpu usage is very high. Is winscp using AES-NI instruction set on cpus which support them?

I'll consider rolling back the "default to Blowfish" change.
AFAIK, PuTTY (WinSCP uses PuTTY code for SSH implementation) does not use AES-NI. I suggest you propose the change to them.

:roll:

I have just tried Bitvise SSH Client (Tunnelier)
so much better

I am converted

i see that this post has been Posted: 17 Nov 2007 15:48
Now its 2013 :cry:

the speed i get is 3000 Kib on a intern gigabit network from Hp server > Hp server
as far as i can see this is way to slow and should be triple that speed

I hope the developers will give the speed isseu high priority because its a very good program with lots of options that no other program has

Hey,

I just wanted to say that after upgrading to the 5.2.2 beta from 5.1.3 my sftp download speed has doubled. :)

Before I could only get 20Mbps, now I'm able to reach 40Mbps.

Still not as good as psftp, which can max out my 70Mbps internet connection, but it's progress. Thanks Martin for your work on performance and I hope to see more gains in the future!

Just wanted to chime in with my experiences. I'm looking for a replacement for filezilla as it is now bundled with adware so WinSCP would seem like a good fit for me, however, I'm getting disappointing metrics when doing a file transfer.

My test task was to upload a Windows Azure hosted web site over regular ftp with ~1000 files at ~100Mb, lots and lots of directories.

FileZilla 3.7.3, 10 threads needs 40 seconds to get this done.
WinSCP 5.5.1, 9 threads, Unlimited speed needs almost 7 minutes.
When I noticed how slow WinSCP was going, I fired up FileZilla and started the exact same file transfer simultaniously to another directory and it finished way before WinSCP did.

This is on Win 7, latest patches, no proxy but probably some Microsoft ISA Server on my gateway to the internet doing funny business transparently with http and ftp connections (I know this because this server has interfered with filezilla before, it doesn't anymore though).

I am in the same position with Sardjent, i tried to use WinSCP as a filezilla replacement but it looks like there is a huge performance difference between the two.

sardjent wrote:

Just wanted to chime in with my experiences. I'm looking for a replacement for filezilla as it is now bundled with adware so WinSCP would seem like a good fit for me, however, I'm getting disappointing metrics when doing a file transfer.

My test task was to upload a Windows Azure hosted web site over regular ftp with ~1000 files at ~100Mb, lots and lots of directories.

FileZilla 3.7.3, 10 threads needs 40 seconds to get this done.
WinSCP 5.5.1, 9 threads, Unlimited speed needs almost 7 minutes.
When I noticed how slow WinSCP was going, I fired up FileZilla and started the exact same file transfer simultaniously to another directory and it finished way before WinSCP did.

This is on Win 7, latest patches, no proxy but probably some Microsoft ISA Server on my gateway to the internet doing funny business transparently with http and ftp connections (I know this because this server has interfered with filezilla before, it doesn't anymore though).

thundergr wrote:

I am in the same position with Sardjent, i tried to use WinSCP as a filezilla replacement but it looks like there is a huge performance difference between the two.

Can you please be a more specific?

Hello,

First of all, thank you for creating such a well designed program. However, i too think there is some kind of performance issue. This becomes obvious if i try to download a folder with a great number of small files. In Filezilla i can set up up to 10 simultaneous connections and download starts immediately. In WinSCP it seems as if the contents of the folder are scanned first, and the program then starts to download one file after another (at least this is what the status window led me to believe), although it already knows the contents of the folder. Is this just my impression or is that really what happens? Maybe that is the cause of the sluggish performance?

Again thank you very much,

Regards,
Paul

It has dragged along for several years now and new patches don't solve anything.

Upload speed is capped at 5 MB/s on a WIRED cat5e LAN !

My router and PC are more than capable of processing the rates.

When I copy a file to remote server, the transfer is capped at 5MB/s. But when I add another file at the same time it also transfers at 5 MB/s. So why on earth are they both transferring at 5MB/s but one cannot go to at least 10MB/s (Even 10 MB/s isn't a great speed.) ?

This subject is very complex, I heard a lot of factors may influence the speed of SFTP, including network latency.
Interesting read: https://stackoverflow.com/q/8849240

Paulus wrote:

First of all, thank you for creating such a well designed program. However, i too think there is some kind of performance issue. This becomes obvious if i try to download a folder with a great number of small files. In Filezilla i can set up up to 10 simultaneous connections and download starts immediately. In WinSCP it seems as if the contents of the folder are scanned first, and the program then starts to download one file after another (at least this is what the status window led me to believe), although it already knows the contents of the folder. Is this just my impression or is that really what happens? Maybe that is the cause of the sluggish performance?

WinSCP can transfer files in queue too. Though is cannot automatically enqueue files recursively yet.

Registered to say most of the stuff in the thread is incorrect, WinSCP has had a cap of sshd file transfers (SFTP) because of the sshd crypto being a single process and maxing out a cpu core for transfer speeds on 1gbps connections, for example one of my 32core servers will encounter max speeds of around 13KiB/s (according to WinSCP) on any single threaded transfer process that is encrypted for the most part..

known fixes are:
https://www.psc.edu/hpn-ssh-home/hpn-ssh-faq/

you'll find HPN as well as what I've said all over the internet for SCP or SFTP, either or doesn't matter or make a difference. SFTP is an upgraded version of SCP.
I've used winscp back quite a few years, if I'm actually on a windows client it's my go to.
having network speed and hard drive speed many times over the "limit" you'll see your CPU max out before anything else does, using HPN you'll see speeds go up without changing winscp


tl;dr your server cpu single threads limit your transfer speed, it isn't winSCP.

Registered to say most of the stuff in the thread is incorrect, WinSCP has had a cap of sshd file transfers (SFTP) because of the sshd crypto being a single process and maxing out a cpu core for transfer speeds on 1gbps connections, for example one of my 32core servers will encounter max speeds of around 13KiB/s (according to WinSCP) on any single threaded transfer process that is encrypted for the most part..

known fixes are:
https://www.psc.edu/hpn-ssh-home/hpn-ssh-faq/

you'll find HPN as well as what I've said all over the internet for SCP or SFTP, either or doesn't matter or make a difference. SFTP is an upgraded version of SCP.
I've used winscp back quite a few years, if I'm actually on a windows client it's my go to.
having network speed and hard drive speed many times over the "limit" you'll see your CPU max out before anything else does, using HPN you'll see speeds go up without changing winscp


tl;dr your server cpu single threads limit your transfer speed, it isn't winSCP.

This is totally wrong for my situation... My i7-4790 is only at 3% Usage for all processes at the writing of this and my transfer speed is only ~500KB/s. I was getting 16MB/s with Filezilla. It is not my CPU, that is for sure. What is it that it limiting me, I do not know. I will only know when the problem is solved.

Snaps wrote:

This is totally wrong for my situation... My i7-4790 is only at 3% Usage for all processes at the writing of this and my transfer speed is only ~500KB/s. I was getting 16MB/s with Filezilla. It is not my CPU, that is for sure. What is it that it limiting me, I do not know. I will only know when the problem is solved.

Thanks for your report.

Can you send me an email, so I can send you back a development version of WinSCP for testing? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

My ftp is going too slow. I'm getting a speed of 1970 B/s. I need help in fixing this problem.

martin wrote:

Snaps wrote:

This is totally wrong for my situation... My i7-4790 is only at 3% Usage for all processes at the writing of this and my transfer speed is only ~500KB/s. I was getting 16MB/s with Filezilla. It is not my CPU, that is for sure. What is it that it limiting me, I do not know. I will only know when the problem is solved.

Thanks for your report.

Can you send me an email, so I can send you back a development version of WinSCP for testing? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

You will find my address (if you log in) in my forum profile.

I was facing a similar situation: version 5.7.6 , low CPU usage (4%) and low speed (400 KB/sec). I solved reverting to Normal debug level (I needed to raise it in the past) and the transfer speed is about 10MB/sec downloading from a remote site.
Hope this helps someone.
Thanks to Martin for the great software.

Methraton wrote:

martin wrote:

Snaps wrote:

This is totally wrong for my situation... My i7-4790 is only at 3% Usage for all processes at the writing of this and my transfer speed is only ~500KB/s. I was getting 16MB/s with Filezilla. It is not my CPU, that is for sure. What is it that it limiting me, I do not know. I will only know when the problem is solved.

Thanks for your report.

Can you send me an email, so I can send you back a development version of WinSCP for testing? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

You will find my address (if you log in) in my forum profile.

I was facing a similar situation: version 5.7.6 , low CPU usage (4%) and low speed (400 KB/sec). I solved reverting to Normal debug level (I needed to raise it in the past) and the transfer speed is about 10MB/sec downloading from a remote site.
Hope this helps someone.
Thanks to Martin for the great software.

I'm experiencing the same download speeds with a similar hardware setup and also using version 5.7.6. I've also tried the different combinations of SCP and SFTP recommended in the FAQ. My observations are that SFTP gives a consistent 700 KB/s to 800 KB/s transfer speeds whereas SCP will initially max out my bandwidth at 4 MB/s but then drop drastically to around 200 KB/s before settling down around 600 KB/s which is still slower than SFTP.

I've also just tried setting the priority up to HIGH in windows for WinSCP but that doesn't seem to have any noticeable effect. I will try out Filezilla and compare the two speeds.

manwe858 wrote:

I'm experiencing the same download speeds with a similar hardware setup and also using version 5.7.6. I've also tried the different combinations of SCP and SFTP recommended in the FAQ. My observations are that SFTP gives a consistent 700 KB/s to 800 KB/s transfer speeds whereas SCP will initially max out my bandwidth at 4 MB/s but then drop drastically to around 200 KB/s before settling down around 600 KB/s which is still slower than SFTP.

I've also just tried setting the priority up to HIGH in windows for WinSCP but that doesn't seem to have any noticeable effect. I will try out Filezilla and compare the two speeds.

Thanks for your report.
Can you try 5.8 beta?
It has some performance improvements, particularly for SFTP.

martin wrote:

manwe858 wrote:

I'm experiencing the same download speeds with a similar hardware setup and also using version 5.7.6. I've also tried the different combinations of SCP and SFTP recommended in the FAQ. My observations are that SFTP gives a consistent 700 KB/s to 800 KB/s transfer speeds whereas SCP will initially max out my bandwidth at 4 MB/s but then drop drastically to around 200 KB/s before settling down around 600 KB/s which is still slower than SFTP.

I've also just tried setting the priority up to HIGH in windows for WinSCP but that doesn't seem to have any noticeable effect. I will try out Filezilla and compare the two speeds.

Thanks for your report.
Can you try 5.8 beta?
It has some performance improvements, particularly for SFTP.

Thanks for the suggestion. I've installed 5.8 beta and the transfer speeds are better. The burst is up to my bandwidth max (around 5 MB/s), but for large files it settles in around 1 MB/s. This may be a limitation of the server I'm downloading from however, since I'm observing the same behavior while using Filezilla as well. Good job on on the performance improvements!

manwe858 wrote:

Thanks for the suggestion. I've installed 5.8 beta and the transfer speeds are better. The burst is up to my bandwidth max (around 5 MB/s), but for large files it settles in around 1 MB/s. This may be a limitation of the server I'm downloading from however, since I'm observing the same behavior while using Filezilla as well. Good job on on the performance improvements!

Thanks for your feedback!

had the same issue. Simple upgrade/re-download if upgrade doesn't work.

Lastest version here, using pscp.exe I get an average of 40MB/s, using WinSCP it starts at 40MB/s and rapidly drops to ~600KB/s.

I'm using SCP protocol, is there some setting that I'm missing?

luizborges wrote:

Lastest version here, using pscp.exe I get an average of 40MB/s, using WinSCP it starts at 40MB/s and rapidly drops to ~600KB/s.

I'm using SCP protocol, is there some setting that I'm missing?

What speed do you get with SFTP protocol?

martin wrote:

luizborges wrote:

Lastest version here, using pscp.exe I get an average of 40MB/s, using WinSCP it starts at 40MB/s and rapidly drops to ~600KB/s.

I'm using SCP protocol, is there some setting that I'm missing?

What speed do you get with SFTP protocol?

I'm using SCP. I tried without Optimize connection buffer size and it worked fine. What this option does?

:evil:

I am using WinSCP to transfer to our ESXis. (Also F5 LTMs, both physical and virtual, and some Linux hosts, and ASA -- though winscp doesn't work with them so just by other means.)

All of these are on the same internal LAN segments ad don;t need to pass through a Router.

We have ether 4 Gb/s or 20 Gb/s availability to transfer to theo hosts based on ethernet networks from differing sources.

Back end is Sata Raid 10 16 Gb/s Fibre or 20 Gb/s iSCSI (Separate bandwidth from the ethernet)

I can can open 10 transfers form the same hose through winSCP, and several more form other hosts, or just one fro one host.

No matter what I do, each thread of the transfer is limited to just over 10 KiB/s

I am using SCP, and I've tried playing with the settings according to the FAQ, and all I can do is reduce the speed by changing to Blowfish over AES 256 (counterintuitive) and optimizing bandwidth reduces me to the same amount as changing the encryption (about 7 KiB/s)

This is not just true for my ESXi hosts, I also see this behavior from my F5 LTMs, and linux hosts.

I can't use WinSCP to send to my ASA (Because you guys don;t have a way to support that AFAICT) but I use putty (PLINK actually) to send to them which is much quicker.

Not sure what the issue could be, i tried playing with every transfer setting and they are set to unlimited.

I also tried to out FTP server using SFTP and still 10 KiB/s while other transfers don't get this limit.

Not sure what else I could do to fix this, but I can't determine anything which is rate limiting these transfers when using WinSCP.

Am I going crazy??!? Maybe!

Anything anyone can think of to try? Maybe it's some setting in the ESXi and devices themselves? But, then why so consistently 10 KiB/s when SCP from ESXi's SCP to some same targets is 30 Kib/s? (I've heard ESXi limits their SCP to this, so I'd be happy to get at least to this.)

Ben

Lurker_QSquared wrote:

:evil:
We have either 4 Gb/s or 20 Gb/s availability to transfer to theo hosts based on ethernet networks from differing sources.

Back end is SSD Raid 10 on 16 Gb/s Fibre or 20 Gb/s iSCSI (Separate bandwidth from the ethernet) depending on which store used. Performance is the same both

I can can open 10 transfers from the same host through winSCP to ESX, and several more from other hosts, or just one from one host, and they'll be 10,000 KiB/s each.

No matter what I do, each thread of the transfer is limited to just over 10,000 KiB/s

I am using SCP, and I've tried playing with the settings according to the FAQ, and all I can do is reduce the speed by changing to Blowfish over AES 256 (counterintuitive) and optimizing bandwidth reduces me to the same amount as changing the encryption (about 7,000 KiB/s)

I also tried to out FTP server using SFTP and still 10,000 KiB/s while other transfers don't get this limit.

Fixed a couple things typos ad grammar just a bit from above.

Anonymous wrote:

Lurker_QSquared wrote:

:evil:
We have either 4 Gb/s or 20 Gb/s availability to transfer to theo hosts based on ethernet networks from differing sources.

Back end is SSD Raid 10 on 16 Gb/s Fibre or 20 Gb/s iSCSI (Separate bandwidth from the ethernet) depending on which store used. Performance is the same both

I can can open 10 transfers from the same host through winSCP to ESX, and several more from other hosts, or just one from one host, and they'll be 10,000 KiB/s each.

No matter what I do, each thread of the transfer is limited to just over 10,000 KiB/s

I am using SCP, and I've tried playing with the settings according to the FAQ, and all I can do is reduce the speed by changing to Blowfish over AES 256 (counterintuitive) and optimizing bandwidth reduces me to the same amount as changing the encryption (about 7,000 KiB/s)

I also tried to out FTP server using SFTP and still 10,000 KiB/s while other transfers don't get this limit.

Fixed a couple things typos ad grammar just a bit from above.

Note, i upgraded my WinSCP from 5.5.5 and now I'm getting a slightly better max-out of speed at about 100 Mbit/s (12.6 MB/s Max reported by the UI) on SCP (I DID have to disable the optimize feature now though, as it would bring me down to about 360 KB/s when enabled.)

on SFTP I'm also hitting the same max speed, so I'm guessing something in the putty code is the limitation now..

Also, I tested SFTP and it was slightly faster than SCP before upgrade no matter how I changed the settings.

I have another environment with the same 5.5.5 code and I'm seeing wildly different values for SCP (1,800 KiB/s max) verses SFTP (11,500 KiB/s Max) Even after changing around the settings several times.

I'll try upgrading that one too, and see if I can at least get it to be 100 Mb/s per stream the way the DR site is for both FTP and SCP now. (Upgraded to 5.10.1 (Build 7725) By the way)

Anonymous wrote:

Anonymous wrote:

Lurker_QSquared wrote:

:evil:
We have either 4 Gb/s or 20 Gb/s availability to transfer to theo hosts based on ethernet networks from differing sources.

Back end is SSD Raid 10 on 16 Gb/s Fibre or 20 Gb/s iSCSI (Separate bandwidth from the ethernet) depending on which store used. Performance is the same both

I can can open 10 transfers from the same host through winSCP to ESX, and several more from other hosts, or just one from one host, and they'll be 10,000 KiB/s each.

No matter what I do, each thread of the transfer is limited to just over 10,000 KiB/s

I am using SCP, and I've tried playing with the settings according to the FAQ, and all I can do is reduce the speed by changing to Blowfish over AES 256 (counterintuitive) and optimizing bandwidth reduces me to the same amount as changing the encryption (about 7,000 KiB/s)

I also tried to out FTP server using SFTP and still 10,000 KiB/s while other transfers don't get this limit.

Fixed a couple things typos ad grammar just a bit from above.

Note, i upgraded my WinSCP from 5.5.5 and now I'm getting a slightly better max-out of speed at about 100 Mbit/s (12.6 MB/s Max reported by the UI) on SCP (I DID have to disable the optimize feature now though, as it would bring me down to about 360 KB/s when enabled.)

on SFTP I'm also hitting the same max speed, so I'm guessing something in the putty code is the limitation now..

Also, I tested SFTP and it was slightly faster than SCP before upgrade no matter how I changed the settings.

I have another environment with the same 5.5.5 code and I'm seeing wildly different values for SCP (1,800 KiB/s max) verses SFTP (11,500 KiB/s Max) Even after changing around the settings several times.

I'll try upgrading that one too, and see if I can at least get it to be 100 Mb/s per stream the way the DR site is for both FTP and SCP now. (Upgraded to 5.10.1 (Build 7725) By the way)

After upgrading that site, the Transfers by SCP are maxing out around 13.1 MB/s, and that is with Optimization ON. Weird.

SFTP is maxing out around 12.4 MB/s but as low as 8 MB/s, and averaging more around 10... That is worse than before and worse than SCP... Maybe because this is an ESXi5.5 server, and the other one is an ESXi6.0

So at least I'm getting the full 100 Mbits that seems to be the limitation in putty, I can

Skylinux wrote:

I'm only getting a transfer rate of 1500KB/s from my Linux server to my Windows computer. The windows computer is running Linux and Windows as dual boot, when I scp from Linux to Linux I get ~8MB/s transfer rate without compression enabled.
I checked WinSCP options and compression is off, I just downloaded the latest version 4.0.5 and it is the same problem.
I need to transfer 25GB from Linux to Windows and WinSCP estimates 4.3 hours, I can burn the files to DVD faster then that....

Any ideas on what is causing this?

There are many potential causes, but in my experience, the stock SCP/SFTP protocols do not scale up in bandwidth very well in the face of any latency in your connection. There are patches to OpenSSH (probably the most commonly used SSH/SFTP server on the Internet) that address all of these protocol-induced performance problems, but the upstream will never accept them into the mainline codebase. Some distros have adopted the patches, like Gentoo.

See: https://www.psc.edu/hpn-ssh-home/hpn-ssh-faq/

You don't need to use the "null" crypto patch if you don't need to eliminate the very last source of performance costs: those of performing cryptography on the data-bearing part of the connection - crypto is *ALWAYS* used during the authentication phases.

Good luck,
Graxl

Hello,

I would to know on my personal laptop the file transfer is very slow but on my office the transfer rate is very high. I don't know how to fix this problem. I have copy the same setting from my lab but still on my personal laptop it is slow.

Please, help me to fix this problem.

Regards,
Asif

Asif_EM wrote:

I would to know on my personal laptop the file transfer is very slow but on my office the transfer rate is very high. I don't know how to fix this problem. I have copy the same setting from my lab but still on my personal laptop it is slow.

Please start a new thread for your problem, and include information about performance of some comparable client. Also mention the protocol that you are using.

I don't get the point. See, directory reading is really slow in long-distance link. Why should NOT we use multithreaded connection (also with connection reuse!!!)? I bet all modern browsers use this technique to increase performance -- even save ROUND TRIP TIME! Is multithreading hard? Does it use too much resources? All I know is that if not multithreaded the directory reading takes forever to complete. Plus the file search is also very slow -- sequence searching? one by one? this is inefficient. There's no way to tune the SSH proto itself actually -- I tried disabling compression but it doesn't seem to work at ALL.

Jared H wrote:

I don't get the point. See, directory reading is really slow in long-distance link. Why should NOT we use multithreaded connection (also with connection reuse!!!)? I bet all modern browsers use this technique to increase performance -- even save ROUND TRIP TIME! Is multithreading hard? Does it use too much resources? All I know is that if not multithreaded the directory reading takes forever to complete. Plus the file search is also very slow -- sequence searching? one by one? this is inefficient. There's no way to tune the SSH proto itself actually -- I tried disabling compression but it doesn't seem to work at ALL.

You cannot multithread directory reading for protocols like SFTP or FTP. There's no API in these protocols to request only a part of a listing.

File search can indeed be optimized by using multiple connections. But that's not that frequently used function. So there's hardly any demand for that.

winscp version:5.15.1 Portable
OS version: win10 1809
linux server version: centos 7.6 mini

winscp options:
close compression
algorithms is DES

WinSCP speed is 400KB/s~500KB/s

Pscp speed is 60/s-70MB/s

anjia wrote:

winscp version:5.15.1 Portable
OS version: win10 1809
linux server version: centos 7.6 mini

winscp options:
close compression
algorithms is DES

WinSCP speed is 400KB/s~500KB/s

Pscp speed is 60/s-70MB/s

What version of pscp? Are you really using ancient DES (not 3DES) with WinSCP? What do you mean by "close compression"? Can you start a new topic for your question? (as this one is quite long already)

doug wrote:

I also noticed that 5.0.7 is much slower, with blowfish I can achieve only around 4MB/s max, with AES I'm getting 10MB/s on 100Mbit network, but cpu usage is very high. Is winscp using AES-NI instruction set on cpus which support them?

This has been implemented:
https://winscp.net/tracker/1769

Please fix the program

I read the manual....still downloads slow