Answered: Problems Reaching Good SFTP Download Speed

Hello, these are some suggestions and comments on this:

• PuTTY's pscp uses the SCP protocol, while our Sftp object uses the SFTP protocol. It would be useful to measure speed of PuTTY's psftp and Rebex Scp object to see how Sftp compares to psftp or how Scp compares to pscp. SCP might actually be faster than SFTP due to the very simple nature of the SCP protocol.

• The aes256-ctr cipher is partly implemented as managed .NET code and is almost certainly a lot slower than PuTTY's implementation. Soon, we plan to add support for aes256-gcm@openssh.com which should be very fast on Windows. This might improve the speed a bit.

• Using a LogWriter might negatively affect transfer speed as well, particularly at the Debug level.

• Have you tried setting Sftp.Settings.DownloadQueueLength to very high value such as 128 or 256? In some scenarios, this has a noticeable effect on download speed.

• We are currently working on a new version of our SSH core that should be faster and more scalable that the current one. This will be available within next year and should improve transfer speed as well.