Hello

this post is about DOWNload speed only.
i'm comparing the download speed of WinSCP (both script and client) vs FileZilla.

i came across WinSCP when i searched for a scriptable free SFTP download client.
it works very well so far, BUT i only noticed now (now that i download more files more frequently for a task in my job): it's very slow

I used to use FileZilla. now, i can't script in that, but it's FAST.
in the default settings (i never played with any settings), FileZilla downloads two files at the same time! and it's showing a much faster speed.

so i downloaded two files totalling 50MB. it took filezilla 30 secs.
in WinSCP, only one file at at time is downloaded, and at a slower speed. took 2 mins for both files.

yes, speed depends on internet connection, but i'm comparing both on the same connection of course

i thought this might be in scripting/shell mode only, but the WinSCP windows client has the same (slow) performance.

what am i missing, what am i doing wrong?
why is WinSCP only downloading one file at a time (in both client and script)?
why is the speed less than half of what i get in FileZilla?
(from the same SFTP source, same internet connection obv).

What version of WinSCP and Filezilla are you using?
What is a transfer speed like? I.e. is you connection relatively slow or fast?

WinSCP can do parallel transfers too:
https://winscp.net/eng/docs/transfer_queue
In GUI only, not in script.
_________________
Martin Prikryl

Hello,

I am seeing this same issue. I have a daily download of a file that is about 30gb in size. Filezilla can pull the files down at up to 1.3 MB/s. The best that WinSCP can pull is about 400 KB/s on the same machine, on the same day. I've already tried turning off the Windows Firewall and it makes no difference.

I hope we can figure out how to speed up WinSCP because I need something that is scriptable. I am SOOOO tired of manually transferring files using Filezilla.

I forgot some info.
- I'm on a 20Mb/s line.
- Using Windows Server 2008 R2
- Filezilla is v 3.9.0.3
- WinSCP is v 5.5.5

Drew Mills

What protocol? Can you attach a log file from both WinSCP and FileZilla?
_________________
Martin Prikryl

winscp on 12m download / 8 m upload line

download 120kbps , upload 62kbps

on all 5 of my servers , which are unrestricted in terms of the scope of this test to the same computers / end points

filezilla on the same line to to the very same computers / servers

download 480kbps , upload 240 kbps and I am hitting ISP bandwidth management now

I was shicked to find this difference after sometime looking at my iptables filters and everywhere BUT winscp .. I see you are asking what version - any version for the last 12months or more

my solution , use filezilla for the transfers and winscp for the permissions and the create link facility -

don't want to get into 'what version , run these tests conversations ' , I have and a simple transfer of a 15mb video file to the same 5 servers , each way , is enough .. you seem to have a limit of 64k up and 128k down in the code , I have a solution , good luck

sorry forgot
what protocol - both ftp and sftp - I thought it may be the encryption so installed ftp on my servers in addition to ssh - result the same !

per previous post not a problem me - filezilla is saving me a lot of time shifting 3 versions of 20m videos around the world - the fantastic world of html5 and three different specs mp4,webm and ogv to cover the visitors - but that somebody else's problem

simple decision - filezilla 60mb transfer to 3 geo located resource servers is 4 times faster upstream push .. ftp or sftp , best D

All users still trying to get WinScp to download at FileZilla Speeds -

answer - 'disable the Nagle Algorythm' on by default in Windows 7 , link below on how to !

It appears that WinScp is using a disk read that invokes / obeys the Nagle Algorythm and FileZilla does not ! .. Apply Fix , Reboot - Solved - WinScp is Transferring at line speed !

https://www.optimizemswindows.com/disable-nagle-algorithm-to-increase-your-internet-speed-for-quick-response/

Thanks for sharing your solution.
Though I'm not able to reproduce your findings. For me WinSCP speed does not change when disabling Nagle's algorithm. Also for me WinSCP is as fast as FileZilla. I have tested this on number of different networks, all with the same results.
Anyway, can you send me an email, so I can send you back a development version of WinSCP, with disabled Nagle's algorithm, for testing? Thanks.

You will find my address (if you log in) in my forum profile.

Was there ever a solution to this? I'm currently seeing the exact same thing - downloading via SFTP using Filezilla v3.10.1.1 maxes out my 50Mbps cable connection, but using WinSCP limits to about 4.9-5Mbps per file. I was originally using v5.5.4 but I upgraded to v5.5.6 and saw the same behavior.

Interestingly, when I had a file downloading via WinSCP script and also initiated a simultaneous download via WinSCP GUI, total download speed jumped to about 9Mbps, so it looks like something might be limiting throughput per file/session?? I tried the regedit fix to disable the Nagle algorithm but didn't see any improvements.

I've run some Wireshark traces comparing a WinSCP download and FileZilla download. The main thing that stands out to me is the TCP window size, and time to send ACKs (keep in mind I have some networking knowledge but am in no way an expert!).

According to Wireshark's calculation Filezilla uses a fixed TCP window of 4194304 bytes from the very beginning, where WinSCP appears to use the more "standard" ramp up technique and hovers around 1700000 bytes once the download gets going. I'm unsure why it doesn't continue to increase. I didn't notice any significant CPU load during either download. I also tried alternating between AES and Blowfish encryption in the WinSCP options but this didn't make any difference (FileZilla uses AES by default).

It's a bit hard to show plots of SEQ/ACK response time, but in Wireshark there is a SEQ/ACK analysis field that gives "RTT to ACK the segment" and FileZilla was consistently around 0.00002s whereas WinSCP seemed to be a lot more inconsistent, ranging from 0.00004s up to 0.00007s


Furthermore, looking more closely at the way the packets are coming in, both downloads follow the pattern of receiving "full" packets of 1460 bytes, until there is one final smaller packet (assuming this is the end of the TCP window), before repeating. The FileZilla download takes 90 packets of 1460 bytes, and 1 packet of 184 bytes for a total of 131584 bytes (I don't know why it doesn't fill out the entire 4194304 window but as I understand it doesn't necessarily HAVE to). This repeated cycle takes consistently 0.017s, giving about 7.7MBps, or 61Mbps. Note that there are still plenty of ACKs being sent back throughout the cycle - about 1 ACK reply per every 2 packets received.

In contrast, WinSCP only takes 11 packets of 1460 bytes before a final 388 byte packet, totaling 16448. Time taken for each cycle varies significantly from 0.0015s up to 0.06s. The 16448 byte transmit window divided by the 5MBps throughput confirms an average cycle time of 0.003s. Again WinSCP is quite inconsistent with the ACKs sent per cycle, ranging from 1 every 2-3 packets received up to 7-8.


So what does it all mean? Well like I said I'm not an expert I would be interested to see if it's possible to fix the TCP window size used by WinSCP to something larger, and I guess maybe looking into the mechanisms of how the two programs process ACKs. FileZilla is open source after all

Thanks for your report.

Is this for a single-file download or total throughput for concurrent downloads of several files?


WinSCP 5.7 has download window of 4 MB too. Please try to upgrade and let us know if you see any change.

This is for a single file download - FileZilla hits about 60Mbps where WinSCP is limited to 5Mbps (per file/session).


Unfortunately I saw no improvement. The behaviour of sending 11 packets of 1460 bytes before a final 388 byte packet over the 0.0015s up to 0.06s timeframe remained consistent even with the increased TCP window.

Let me know if you'd like any other testing done - WinSCP's scripting interface sets it apart from all the rest so I'm more than happy to help with any improvements!

Do you see at least the increased TCP window?
_________________
Martin Prikryl

Yes I can see it has been increased and is fixed now so in that sense it seems to behave like FileZilla, but no other change with actual throughput. It still looks quite unstable in comparison.

Thanks.
I have sent you some binaries for testing via email.

Here are the results:


Files in email:

psftp.exe - downloaded at 46-48Mbps via command line interface

psftp_32.exe - downloaded at 46-48Mbps via command line interface

psftp_64.exe - downloaded at 46-48Mbps via command line interface


FileZilla - consistent 61-62Mbps

WinSCP v5.7 - 4.9Mbps via standalone GUI app

WinSCP v5.5.4 (original version my scripting is set up with) - 4.9Mbps via standalone GUI app

I then went and checked my existing psftp.exe in the directory where I have been using the standalone WinSCP application, and it also downloaded at 46-48Mbps via command line. I guess there an issue somewhere with how the WinSCP application interfaces with psftp?

Thanks for your comprehensive tests.
Could you please enable Debug 2-level logging in WinSCP and attach a log from the test?

I have sent you an email with the download link as the filesize is quite large.

Thanks

This issue has been added to the tracker:
https://winscp.net/tracker/show_bug.cgi?id=1295

Hello,

I noticed (especially visible on larger files) that WINSCP download speeds are 3-6 times slower than other FTP clients. Since I have to script my download, WINSCP more or less my default choice due to various features present.

Here what I observed:

Same MS windows 2008R2 server.
Same Destination.
Same file.
Protocol: FTP
file type: ZIP

WINSCP 5.7.1 - ~975 KB/s
Filezilla latest - 6.7 MB/s
Windows ftp client - 3767 KB/s

this was observed over long period of time, and numbers are very consistent.

I tried few suggested -rawsettings options but results did not change.

BUG tracker said it fixed in 5.8, can this version be obtained (to be tested) yet?

There's improvement for high latency connection. So I cannot tell, without more information, if it helps in your particular case.

Anyway, I have sent you an email with a development version of WinSCP to address you have used to register on this forum.

server is 48ms away from me.

running dev version of WinSCP against the same file

download spped between 974 KB/s to 1004 KB/s

Thanks. Please attach a complete session log file on Debug 1-level for the download.
_________________
Martin Prikryl

Prikryl, I am having a similar problem to this. Would it be possible to email me a preview version of 5.8 to test also?

Thanks

Can you send me an email, so I can send you back the development debug version? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

You will find my address (if you log in) in my forum profile.
_________________
Martin Prikryl

I am glad to report that download speed from far endpoints are much more faster with latest nightly build. Prague to Miami went from 600 KBps to 4000KBps. That helps!

Thanks for your feedback!

I'm afraid I'm experiencing this problem.
How can i get a 5.8 beta to test if it fix also slowness I'm experiencing?

thanks

bye

Marco

The same: Can you send me an email, so I can send you back the development debug version? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

You will find my address (if you log in) in my forum profile.

just sent e-mail to you.
thanks

Marco

can i get a copy of the 5.8 beta too? bruno0502@hotmail.com

Bruno

Hi, I'm having the same problem, uploading the same file takes a lot longer with Winscp tha with Filezilla.
Could you send me th v.8 please.

Thanks.

jpcr@markdata.pt

Hi, I've just noticed that if one sets the option transfer binary, the speed equals the one of filezilla.

Best regards,

I am trying to set up a connection to a site in China for an upcoming test and I am running into the same issues described here, I have a decent bandwidth but a high latency and my transfer rates are <100 KB/sec. I would be very interested in trying the 5.8 beta, I'll let you know if there is any difference.

Sent.

Thanks for your dedication prikryl!

Would you please send me the latest test version?

Sent.

I also experience very slow transfer speed in winscp as opposed to filezilla and I decided to test things in winscp 5.8.2 beta. I ran a couple of tests and found no real difference between 5.8.2 beta and 5.7.x - probably the improvements don't apply to my network connection.

My observation is that winscp is equally fast to filezilla when a single big file is transferred. The big differences start when I transfer a lot of small files. Let me share my test results for both winscp 5.8.2 beta and filezilla 3.16.1, both run in portable mode.

The results are for 2 servers, server A is located in a much further location and slower than server B. With server A I used plain FTP, for server B I used FTP with TSL/SSL Explicit encryption. In each test I transferred 125 files and 16 filders, which are 3.08 MB total. I used background transfers and test 2 and 4 simultaneous transfers settings.

My connection speed as reported by speedtest.net:
download: 15 Mbit/s
upload: 26 Mbit/s
ping: 22 ms

Results:

Download:

2 simultaneous:
winscp: A=01:37 / B=01:27
filezilla: A=00:31 / B=00:26

4 simultaneous:
winscp: A=01:26 / B=01:31
filezilla: A=00:19 / B=00:17

-------------------
Upload:

2 simultaneous:
winscp: A=02:02 / B=01:11
filezilla: A=00:44 / B=00:33

4 simultaneous:
winscp: A=02:01 / B=01:24
filezilla: A=00:30 / B=00:21

-------------------
Delete:

winscp: A=00:26 / B=00:22
filezilla: A=00:20 / B=00:09

As you can see the differences are quite huge. I don't know why winscp is so slower for large number of files. I hope this can be improved because currently whenever I need to transfer a set of files fast I need to switch to filezilla instead of doing everything in winscp.

Thanks for your report.
Did really WinSCP transfer 2/4 files simultaneously during the whole test?
I ask because WinSCP does not support recursive parallel transfers atm.

By simultaneous transfers I meant the setting "Maximal number of transfers at the same time". Filezilla has a similar setting "Maximum simultaneous transfers" and I tested both programs at setting 2 and 4.

I don't know if these settings work the the same in winscp and filezilla. Filezilla will transfer multiple files at the same time when processing the queue and this usually speeds up quite a lot, especially for a lot of files. I don't know if winscp does the same under the hood but as you can see from the results increasing the number has small effect in winscp (if any) while in filezilla it improves the overall speed considerably. Maybe filezilla is faster because it uses parallelism better than winscp?

Please try this:
Select files in one folder only (no subfolders). On the Transfer option dialog, make sure you check Transfer on background and Transfer each file individually

Okay, ftp download test of 500 files, 1.81 MB total:

winscp, background, each file individually: 01:53
winscp, normal background transfer with 2 maximum transfers: 03:35
filezilla with 2 simultaneous transfers: 01:30
filezilla with 4 simultaneous transfers: 00:46

When transferring each file individually winscp used a lot of CPU and the file and queue list refreshed constantly with some visual artefacts and winscp's UI was overall less responsive.

Thanks for your test. Can you try the same with WinSCP 5.8.2 beta?

All these tests were done with 5.8.2 beta.

I made one more test on an even ground and I set all simultaneous connections to 1. The same set of 500 small files downloaded via FTPS:

filezilla: 03:07
winscp: 03:57

Thanks for the details. We will look into it.

I also have the similar issue: on several windows and linux hosts copied 1 large file from the same sftp server via 1Gb lan:
fillezilla v3.20 @ windows 2012 : ~32 MiB
scp @ debian8: ~33 MiB
WinSCP v5.91 @ windows 2012 : ~16 MiB (scp or sftp mode - no difference)
pscp @ windows 2012 ~17 MiB (scp or sftp mode - no difference)

WinSCP is very useful in scripts, so it would be great to find a way to speed it up.

scp in Cygwin works as great as in Linux