IMAP Performance

[karlp at ourldsfamily.com]

As I prepare to move to a faster server, I am seeing the old server bogged
down significantly by imapd. How must faster are the various IMAP servers
available. I've heard a few names, such as Courier, WAimap, but have no
experience with installing, configuring or maintaining anything other than
the default imap server that comes with RH (rh6, rh7, rh8, rh9 and now
FC4).

Any help or suggestions are welcome.

Thanks,

Karl