Fixing & Improving SpamAssassin Performance

The file /etc/sysconfig/spamassassin comes as:
SPAMDOPTIONS="-d -u qmailq -c -H /var/qmail"

where the options are: -d daemon -u run as user... -c create users' preferences files -H work directory...

But it can be improved with: -x (server, don't check users' files) -q (users' prefs stores in sql db) -L (local, don't perform dns checks) -m10 (10 childs)

so, a very fast and light (but not powerful) config would be:
SPAMDOPTIONS="-d -u qmailq -x -L -m5 -H /var/qmail"

It's important to add the -m10 or -m5 flag, because by default SpamAssassin is not limited - it can spawn 1,000 copies if you're not careful (bringing your server to it's knees). So I always limit the number of spamassassin copies that are allowed to run at once.