It's apples and oranges to some extent since most Windows or GUI av
scanners have a realtime component which most users are interested in.
There are no comparative detection tests that I know of. It's hard to
say until at least a good ITW comparison test is available. I can say
that clamav is reacting promptly to new malware submissions. I suspect
that it's quite useful as a backup "second opinion" scanner for many
users.
The last time I checked, a couple of months ago. The scan was a bit slow
becuase the database has too many entries with common prefixes in it. Uses
an aho-corasick prefix scan (of length 4, I think) then checks the remainder
of signatures with that given prefix. It didn't do emulation to detect
polyporphic viruses then either.
