Ok, my bad. Here we go:
- after successful upload FTP tab is reloading causing whole program to freeze
- the same goes for disconnecting from ftp server - program freezes for a few seconds
- sometimes uploading files is very slow. Uploading 100 of *.jpg using external FTP client (like FileZilla) takes a few seconds, using Multi Commander it takes a few minutes (one 100 kB file is uploading for more than 30 seconds). I did not found out what is the possible cause here (for sure it is not upload speed). It not happens always, but quite frequently.
Abandoned WinXP user here. And it won't change any time soon.