Avast! is a bit resource intensive to, although about the same as
AVG was around 3-4 years ago. I see Avast! slowly creeping the
same direction as other malware boatware as well though.
That is probably true - just about every software package piles on
questionable features to make it look like they are advancing and
staying competitive with their peers. Fortunately, Avasts extra
features can easily be disabled. I have mine pared down to the two or
three services I think are important, and have turned the others off.
In this mode it seems to use a reasonable amount of resources.