I noticed that CURL SFTP is way slower compared to CURL FTP.
When I say slow, I would say A LOT slower. This seems to be the read data buffer used in CURL (16KB ?) and immediately becomes a bottle neck in itself.
Anyone have experience using CURL with SFTP? Any hints how to speed up things?
BTW I use CURLMBS
This seems to be a problem with libcurl rather than CURLMBS.
I know it is not a problem with CURLMBS. Just asking if there are some things you can do to make it faster. 
slow? I use SFTP all the time.
Well, I could recompile plugin with CURL_MAX_WRITE_SIZE being bigger.
[quote=229797:@Christian Schmitz]slow? I use SFTP all the time.
Well, I could recompile plugin with CURL_MAX_WRITE_SIZE being bigger.[/quote]
Yes, terrible slow compared to FTP. It is a known issue with CURLFTP. But making the Max_write_size bigger seems to be a solution. As read in the above link.
Please try pr6 later tonight when upload finished.
Did some tests. It does several transfers (reading a directory, downloading some small files).
PR5:
FTP : 2 secs
SFTP : 21 secs
PR6:
FTP: 2 secs
SFTP: 2min 38secs.
I tried with several OptionBufferSize settings but nothing improved the SFTP handling. In other words compiling Curl with 1MB max buffer isn’t making it better … but much worse.
54 MB file upload in LAN via SFTP.
14 seconds with pr6 and defaults.
same for using buffer size 1 MB.
and same with pr5. No change for me.
So maybe you check logs and see what takes so long.