A Question of Debian ClamAV, Freshclam and Volatile

I’m not a big fan of virus-scanning on the mailservers (I think you should bolt your email-sending computers right down so that viruses and spambots can’t send email), but it seems to be a necessity these days. So, I was a bit late starting on mailserver-antivirus and mainly pay attention to it when it goes badly wrong. I’ve got clamav installed where needed, but recently I’m seeing clamav hang, eat CPU and cause postfix to defer all emails while logging nothing useful. Often this seems to be soon after freshclam kicks in. Anyone else seen this problem? Moreover, anyone managed to narrow it down and fix it?

On some systems, instead of having freshclam, we have clamav-data from volatile which seems to work better, but are they missing out on anything by doing that? Does it lag a bit behind and download a bit more?

Is there a third option, either another way of feeding clamav, or an alternative debian package, which you think people should consider?