Performance Issues with Spamassassin

[Anthony and Mary Ann Tantillo <amtantillo@earthlink.net>]

I have begun using spamassassin (2.01) with razor (1.19) as a mailfilter
in combination with fetchmail (5.9.8), procmail (3.2.2), and exim (3.3.4).  
When I fetch a large number of messages (e.g. when I first startup the
computer), response slows to a crawl. If I monitor the processes using 
top, spamassassin processes start to fill the screen.  On a
recent download of 119 messages, top indicated that linux began to 
shutdown processes to accomodate the load (mysqld was one of the first
to go).  What am I doing wrong?  I copied the procmail formula from 
the example at the top of the .procmailrc file and even shortened my
list of filters that I have been using. I thought that there might 
be a procmail backup.  My computer has a 800 MHz Duron with 128 MB of
RAM and 512 MB of swap.  (I had hoped to add more memory quickly 
when I first assembled the computer; I know that this is not optimal). I
am using woody and running kernel 2.4.17.  
I also use shorewall as my firewall.

Tony Tantillo