Running Postfix + AMaViS + Clam AntiVirus

I have just got Postfix on my Mandrake Linux box to talk to Clam AntiVirus via amavisd-new, which also does spam filtering as well. It uses Postfix's content filtering interface to pipe the incoming emails through another SMTP server to quarantine potential viruses. Because AMaViS also integrates with Spam Assassin, I have thus dropped my procmail script that does spam checking at local drop.

The installation is quite straight forward, except maybe the Perl modules as I have a broken CPAN configuration. Everything seems to be working fine so far. Last night it has successfully quarantined 20+ incoming Worm.SomeFool.Gen-1, one Win32.Yaha.P and a few different spams. Still trying to work out who is that MTS guy on the Optus network that has caught the virus...

The only complain I have is probably the amount of resources it requires to run Clam AV + AMaVis. When the daemons bootstrapped, clamd uses around 12Mb RSS and 3 instances of amavisd are running at 20Mb each! Scanning each incoming email would take at least 3 seconds on my aging dual 400Mhz Celeron. I wonder how would a large deployment would cope.