[Exim] Timeouts using Spamassassin

After installing Spamassassin onto my system, I seem to be getting lots
of timeout problems. I have a pretty ancient system, so perhaps this is
the problem.. It's a Pentium 166, 80 meg ram on a dialup connection.

It seems that 30 or so emails don't give any problems, but when I get 90
or so, I get many timeouts.

Basically, I am using spamc/spamd implementing the mods found on dman's
website.

Here is an example from mainlog for one message:


2002-09-16 16:29:43 17r3R7-0000Hy-00 <= debian-security-announce-request@??? H=localhost.localdomain (localhost) [127.0.0.1] P=esmtp S=17122 id=Xb-rrB.A.1iF.EwUh9@murphy
2002-09-16 16:35:05 17r3R7-0000Hy-00 ** dlb@localhost D=spamcheck_director T=spamcheck: pipe delivery process timed out
2002-09-16 16:36:13 17r3XB-0000U9-00 <= <> R=17r3R7-0000Hy-00 U=mail P=local S=18027
2002-09-16 16:36:18 17r3R7-0000Hy-00 Error message sent to debian-security-announce-request@???
2002-09-16 16:36:20 17r3R7-0000Hy-00 Completed

If I remember correctly, in this download, out of 288 messages, I
received some 178.

Earlier, I had even gotten some data timeouts..

In an attempt to fix this, I have increased all timeouts that seem to
make a difference.

I've set smtp_receive_timeout, command_timeout, and data_timeout all to
10m. The obvious (to me) culprit, pipe timeout, defaults to 1h, and
exim -bP verifies that this is, indeed what it's set at.

As noted above, however, this message timed out at 5 minutes.. so.. what
timeout would affect this, and is it alterable?

Is there some way to fix this, or do I just not have enough horsepower
to run Spamassassin?

The only other possibility I've considered is whether Spamassassin
checks the online rbl databases on each download, or each message(?)