Slow LIST command

[Richard Gilbert]

We are providing a webmail service to this year's new students (< 8000)
based on IMP.  I am running Cyrus imapd version 2.1.9 with Berkeley DB
3.3.11 on a Sun 420R with 4 x 450 MHz processors and 4Gbytes of memory,
but it is on its knees at busy times.  Now maybe the hardware isn't beefy
enough for the load which IMP puts on the server, but I was given the
impression that because Cyrus is so very efficient it would not be a
problem.

Having watched the activity, the thing which seems to consume most of the
resources are the LIST "" * and LIST "" % commands.  These return with a
response like "OK Completed (1.480 secs 28 calls)" but can take a very
long real time.  Is there anything which can be done to speed up the
performance of the LIST command?  My imapd.conf is appended.

TYIA

Richard
--
Richard Gilbert
Corporate Information and Computing Services
University of Sheffield, Sheffield, S10 2TN, UK
Phone: +44 114 222 3028   Fax: +44 114 222 3040

configdirectory: /var/imap
partition-default: /var/spool/imap
partition-imap2: /var/spool/imap2
admins: cyrus exim
sasl_pwcheck_method: saslauthd
sasl_mech_list: plain
hashimapspool: yes
altnamespace: yes