why is WinSCP so slow

Question

the interface is handy but the file transfer rate is freakishly slow compared to pscp or scp in my VM on the same windows machine. i'm only getting about 17kb/s when my overall connection speed can go up to about 1Mb/s (what i've seen not what my provider tells me they're giving me) and i'm pretty sure i've connected to the same computer at much higher speeds before

Answer 1

You might find the File transfer speed FAQ on the WinSCP site useful, I'll provide the basics:

The SSH code of WinSCP is based on PuTTY, so file transfers with the SSH-based protocols cannot be expeceted to be faster than PuTTY. So it might be worth trying a file transfer with PuTTY directly to see if it is comparable.

As well as bandwidth, they suggest that there are two common limiting factors in overall connection speed for WinSCP: CPU and Connection Latency.

CPU

Is important because everything that is sent has to be encrypted at one end and decrypted at the other (and potentially compressed as well if that is enabled). If either machine is slow enough (or happens to be working on other things) the overall connection speed will have to be reduced so that CPU can keep up with the encryption / decryption / compression procedures.

The suggestion here is to use a less intensive encryption method (they suggest that using Blowfish is usually faster than AES), try disabling compression and try moving down to SSH-1 if using SSH-2.

Connection Latency

They suggest trying the SCP, protocol instead of SFTP, as SCP is less affected by latency (and they suggestion turning on compression in this case).

Answer 2

See if you have a hard limit in 'transfer', in "preferences/Other preferences". Could happen if that machine have been used/configured by someone else. The VM config could be affecting, too.(or intermediate nodes)