I suspect there may be more to it than this.
We regularly upload video files that are 100Mb+ with no problems at all.
Obviously, a tar.gz would need to be unpacked twice before it could be scanned, which would not be the case for a video file.
ALSO, I expect there's a setting somewhere that says don't scan files that are more than X Mb in size, so maybe they aren't getting scanned at all.
But I really don't think a 2Mb ta.rgz file should tax Clamd at all.
Have you tried disabling the Google Safe Browsing rules, in case the increased memory overhead these add to clamd might be a possible cause? Obviously this is not ideal, but it is better than switching it off completely I suppose.
Nope thats not the thing. If I send a 40-50 mbyte tar.gz with normal files it passes through very fast.
But some files such as zipped databses make clamd consume the whole cpu for a heck of a long time !!!!