performance issues tonite

[David Vosburgh]

I'm using MS 4.21-9 and SA 2.60 (upgraded two weeks ago), no
DCC/razor/pyzor on a Sun 220R with 1GB memory and 2x450Mhz.  Tonight I
noticed that our incoming mail queue started backing up about 6pm CDT,
and delivery times were growing quickly.  It peaked about 9:30pm and has
been working it's way back down slowly since then.  I've only got about
150 messages in the queue now.  During this time, the maillog is
indicating that SA is timing out:

Oct 23 22:03:36 xxxxxxx root: [ID 702911 mail.info]
MailScanner:SpamAssassin timed out and was killed, consecutive failure 1
of 20

I haven't seen more than one consecutive failure.  I've read on this
list about this being related to SA's RBL checks, but I've got them
disabled (skip_rbl_checks 1) in spam.assassin.prefs.conf.  The load on
the system is about what it usually is (load average between 4 and 6,
with CPU smacked pretty good but ~85% user).  There's not an abnormal
amount of mail being processed.  Nothing like with the Sobig outbreak.
 FWIW, I've got Max Children = 5.  Any suggestions on what else could
cause the timeouts?  Thanks.

Dave