I have a 2G BigV. Clam was taking > 20% memory.
The earlier incarnation as 3G. The 3G was dead on its feet and I couldn't face the death by 1000 cuts on the new machine.
I will look at your spamcop comment.
I've certainly seen clamav 'events' in the past - the most recent (a long time ago) saw freshclam spit about half a million lines into the log file in a second. I think the .conf can protect against that but I'm not sure if it does under vanilla symbiosis.
Re-enabling clamd to see how long it takes to be wrong ... I'll back off at the first sign of trouble.