Performance problems, compared to wu-imapd

[Tuomas Toropainen]

I have been running some performance tests on my cyrus test installation.  
The computer is not very fast, but my intention was just try how cyrus
performs compared to wu-imap on the same computer. It's 350Mhz P2 with
256MB memory and 4,5GB scsi disk. OS is redhat 9 and filesystem ext3. I'm
using mozilla mstone as benchmark program, and also when it has been
running, I have used squirrelmail to see how slow the imap service gets.
Mstone and squirrelmail are being run on other computers.

The problem is that wu-imapd seems to perform much better than cyrus.  
Cyrus version is 2.1.16, compiled with default database options. Syslog is
not logging debug messages, and has synchronous logging disabled (-). Both
systems have 500 test users, about 100 mails per user in INBOX. Mails are
generated with postal and are random text, max 20kB size. I also tried
with 100 users, the results are much same. Mstone results, squirrelmail
speed and computer load all tell that wu-imapd is faster.

For example, with 500 users, using cyrus mstone managed to retrieve 8,730
messages during 5 minute test, averaging 652.70ms per message. But using 
wu-imapd, 33,709 messages were retrieved, averaging 15.71ms per message.
Maximum concurrent connections was a little lower with wu-imapd (~180 vs 
220), but with cyrus computer load increased to 150 when there were 190 
imapd processes. Wu-imapd caused a maximum load of ~15.

What am I doing wrong, or is this computer just too slow for cyrus to 
perform well? Or are the default databases so poor that they cayse this?

Complete results are at 
http://www.cc.jyu.fi/~tjt/imaptestit/cyrus/results.html (cyrus)
and http://www.cc.jyu.fi/~tjt/imaptestit/wu-imapd/results.html (wu-imapd)

Thank you for any help :)