I don't know if this is clamav related problem or ISPConfig, but I'm posting here, because I think it's important to ISPConfig too.
I've installed http://www.ispconfig.org/downloads/I....7-beta.tar.gz
and here is what I noticed.
The first screenshot is made 1 minute after starting the machine, then you can watch the clock in the corner.
The machine has CPU Celeron 300Mhz and 256MB RAM.
You can see there clamd is using 5.1% of the memory and the CPU usage is 99.7%.
1.5 hours later the CPU usage is still 99.7%, the memory used by clamd is now 12.6% and all the CPU's time is used by it.
Another 1.5 hours later - the CPU usage is 0.7%, the memory used by clamd is 21.7% and the used CPU time is 3 hours.
So my conclusion is: clamd is doing a lot of calculations using a lot of memory (about 50MB) and this continues about 3 hours.
Is this behavior normal?
Edit: I've noticed amavisd-new is also using a lot of memory - about 128MB.