Variable download speed with WinSCP

Hello,

I have some problems download speed with WINSCP. I used before FileZilla.

• My connection is 500/400 Mbps.
  
• Windows 10
  
• Gigabit switch
  

With FileZilla, my downloads were around 60 mb/s in SFTP.

With WinSCP with same distant connection :

• Download to my computer : 30 Mb/s
  
• Download to a network drive on my network : never exceed 8,5 Mb/s...
  

Direct transfer between my computer with a network drive is 80 Mb/s.

How can I resolve this problem ?

What protocol are you using?