Bug 164 – Slow file transfers

Component: Core

Version: Unspecified

OS: Unspecified

Severity: Enhancement

Priority: Medium

Implemented/Fixed in: 5.8

Resolution: FIXED

Status: RESOLVED

Votes: 0

Description
2008-02-28 10:18

Many users report WinSCP not to utilize all available bandwidth.

This topic is discussed in FAQ:
https://winscp.net/eng/docs/faq_slow

Comment #1
2008-02-28 10:26

Releated: Bug #1, Bug #17.
Also WinSCP 4.1 will support (less secure) Arcfour cipher, which should be fast.

Comment #2
2008-02-28 10:52

WinSCP (FAR plugin 1.5.1 base on WinSCP 3.8.2) is as fast as PSCP (8 MB/s) and SFTP (3 MB/s) (PuTTY 0.60):
https://winscp.net/forum/viewtopic.php?t=3137

WinSCP 3.8.2 is as fast on upload as SSH Secure Shell 3.2.9, but much slower on download on WinXP. On Win2K it is as fast:
https://winscp.net/forum/viewtopic.php?t=4684

Transfer rate is capped at 100KBps:
https://winscp.net/forum/viewtopic.php?t=5277
https://winscp.net/forum/viewtopic.php?t=5313

SCP significantly faster than SFTP:
https://winscp.net/forum/viewtopic.php?t=5096

https://winscp.net/forum/viewtopic.php?t=2455

PuTTY 0.59 much faster than 0.58:
https://winscp.net/forum/viewtopic.php?p=14104#14104

Comment #3
2009-03-02 08:22

4.2.1 almost twice as fast as 4.1.8 on Windows Vista:
https://winscp.net/forum/viewtopic.php?t=6614

Comment #4
2009-07-03 08:13

Suggestion for fixing network speed after installing SP2 for Vista:
https://winscp.net/forum/viewtopic.php?p=24994#24994

Comment #5
2009-08-19 08:39

Fixing network speed in WinXP:
https://winscp.net/forum/viewtopic.php?p=25801#25801

Comment #6
2010-10-16 20:46

It has been suggested by ultramage that increasing SSH socket buffer size may instead transfer speed. See Bug 615.

Comment #7
2011-11-11 09:35

Bug 615 has been rolled back by Bug 677 as some users were having problems with it.
The fix was reintroduced by Bug 690, with option to disable it, in 5.0.3.

Comment #8
2016-05-17 09:33

Bug 787: 5.0.6: When Optimize connection buffer size is enabled, also FTP socket internal buffer size is increased.

Comment #9
2016-05-17 09:33

Bug 1141: 5.2.2: Increase local SSH send buffer to improve performance

Comment #10
2016-05-17 09:33

Bug 1273: 5.7: Size of connection receiving buffer increased.

Comment #11
2016-05-17 09:34

5.8: Improved transfer speed:
- with SFTP and SCP protocols when CPU is limiting factor.
- with SFTP on high latency connections Bug 1295

Comment #12
2016-05-19 09:21

5.8.3: Dynamically increase TCP send buffer on fast connections.

Comment #13
2018-01-11 09:09

https://winscp.net/forum/viewtopic.php?t=25705

Comment #14
2019-06-14 09:13

S3 specific entry: Bug 1732