I am able to access my Cent OS 5.5 64-bit linux vps through Putty with no problem. But when I try WinSCP or FileZilla it just usually hangs on login. Sometimes I actually am able to login but then it hangs trying to display the first directory contents. Sometimes I get in for a few minutes, can transfer files, and then it hangs or is unbearably slow. I messed with all sorts of connection settings in both programs but no luck. What would cause this sort of slowness and frequent connection issues. Usually when I have a problem, Putty is open in another window (not always though) and that connection stays strong.
My /etc/ssh/sshd_config file correctly has this line enabled:
Subsystem sftp /usr/libexec/openssh/sftp-server