If you connect via a 28.8 modem, F-Secure SSH is rather slow. One workaround is to turn off compression. If you turn off encryption, then your passwd will be sent over in clear text. The SSH faq suggests using blowfish if performance is an issue. Also, make sure that you are not attempting to compress your session too much.
Compression is good for downloading large files, but can slow the response for interactive sessions.
You might also try turning off Enable modem compression under the Basic tab and Configure . If you are not in the local group, then contact F-Secure support for the patch. SSH-1.1 might also help. If you are running under NT, you might try getting the 32-bit SSH1.1 client from DataFellows. Locally, we have a copy of this, see the NT localization page.