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Ok, so I tried out pscp and psftp, v 0.60. PSFTP : 3 MB/s. PSCP : 8 MB/s (same speed as in WinSCP). It is actually not that stable : +/- 15% in the same mode quite possible (probably due to the network load).

But in any way, I ***NEVER*** saw transfers faster than 12 MB/s under Windows. Pretty desperate. As I said, I do NOT think it's a bug in WinSCP (but rather in this W word operating system). However, I hoped I could find some help in this forum, since winscp's main goal is to copy files over the network...

I would like to set up an extra test to be sure that it's Windows fault. Namely, set up a local FTP server (not SFTP) and to see what the speeds are under Windows and under Linux. But we don't have it on my work...

If anyone has the possibility to do this test, it would be great.

Of course, it won't give us an answer on how to speed it up, but it's some progress.

P.S. By the way, in my original postI said "setting encryption on". I meant of course "setting compression on".

That almost implies that there is a problem with the throttling code (the slider that does 5% - 100%). Perhaps it's active when it shouldn't be?

I believe that there is no such error.

Can you try PSCP/PSFTP for comparison? WinSCP SSH code is based on PuTTY package. I cannot make WinSCP faster than they are.

It's interesting to note that DNFs performance degradation is nearly exactly the same percent as ours, but with much higher numbers. That almost implies that there is a problem with the throttling code (the slider that does 5% - 100%). Perhaps it's active when it shouldn't be? Or measuring off the wrong number or something.

We also recently upgraded our net connection and we saw a boost in performance of WinSCP -- but it's remained at the same fractional percent of our connection.

All very strange... and unfortunate; it hurts productivity a ton.

... sorry posted it before I finished the last sentence ...

.... I am using WinSCP every day and this is quite a bothersome issue. Any help would be very much appreciated!

Thanks in advance.

Hi,

I also have the same problem. Winscp (FAR plugin) starts copy at about 12 MB/s, then after about 8 seconds drops to 8 MB/s. This is with blowfish / no compression / scp. I played with all the settings and this is the best figure I get. Setting encryption on and changing encryption to AES slows down but insignificantly (6.5 MB/s).

One can say that 8 MB/s is fair enough... but I have the dual boot machine. Under Linux I get ... 40-45 MB/s. It's factor five and it makes a lot of difference for me (I often transfer very large files). So now I actually reboot to copy files, it's much faster than to do it under Windows. Which is not the point of WinSCP, is it?

I looked through various forums but never found an answer.

More details :
* FAR plugin 1.5.1 (based on winscp 3.8.2, putty 0.58)
* 1 Gbit/s network. Copying from Linux server. Linux server workload is zero (except myself). We are in the same subnetwork (on the same switch).
* I did it with windows firewall on and off. No influence.
* QoS scheduler is off.
* I have no resident antivirus or any other stuff like that.
* I run Windows XP SP2.
* I have had this problem on two different computers.

I actually thinkit's a problem with Windows network layer

Please read FAQ.

It varies in other situations too. The test I did above was btwn an AMD64-3000 and an AMD Athlon 1800+

On say a PIII, the cipher or zlib difference matters more.

Compression enabled or not with WinSCP ? Compression tends to be a killer too.
I just did a little testing, and yeah, aes256-cbc is still 11MiB/sec, but throw in zlib compression, and we now go to about 7.5MiB/sec. Using normal rsync or scp that is, not WinSCP.

Thought about on-access virus scanners? Those are a killer too.

Winscp is still very slow. Scp between 2 linux boxes can give me 10+MB/s easy.

Encryption tends to kill xfer speed on LANs, as it becomes a bottleneck.

Suggestion here would be to support the request for Arcfour to be supported (relatively insecure, but MUCH faster, encryption algorithm). I Don't recommend arcfour for untrusted networks, but for trusted networks it's fine. In theory on trusted networks you can use no encryption, but ssh doesn't support cipher none w/o patching.

Thread about arcfour and WinSCP is here: https://winscp.net/forum/viewtopic.php?t=569

When using winscp to access the box that is locally in the network and transfering files it goes SO slow , around 1600 kb/s .

But when using ftp the speed is normal , 9500-10000 kb/s

?