I made the cache non-permanent, still I don't get what this cache is for in future sessions if all it stores is a list of visited directories.

The cache entry is identified by the hostname/username, so that it is used, no matter if you have stored session/site for that combination saved or not.

You can turn off the cache completely (not recommended) or make it non-permanent:
https://winscp.net/eng/docs/ui_login_directories

I store WinSCP settings in the registry, and when I make backups by exporting the branches like
HKEY_CURRENT_USER\Software\Martin Prikryl\WinSCP 2\Configuration
the backup file is quite large (~1Mb) because of the CDCache node. If I clear it the reg-file become quite small. Of course, the same info is stored in the registry and it is no good to store so much info there.

1. WinSCP seems not to delete CDCache nodes of deleted sessions. If I delete a session its node in CDCache is still there. Thus if I use WinSCP for years, the CDCache node only keeps growing.
Also, the CDCache node stores info based on the username / the server IP, like cust@12.34.56.78. But if I edit a session's IP / username (sometimes that happens) the old node is probably not changed / deleted, while it should be. Hence the CDCache node unnecessarily grows again.

2. Why have CDCache at all?! I need it within a session for history, to be able to go back and forth. But can I ever make use of it if I restart a session?! If not, why keep the old info?!

:?:

It is cache for visited directories.

Hi, I'm doing a forensic ana lysis of a computer (a fake one set up by my teacher for my coursework so don't worry :p), and there's information of connecting to a server in the HKEY_CURRENT_USER/Software/Martin Prikryl/WinSCP 2/Configuration/CDCache. I thought this was a sort of 'log' for FTP/SFTP connections, however I am not able to reproduce this registry key (no CDCache folder exists on my machine).

Does anyone know what this signifies?

Thanks