I notice this problem the other day after I got an update to the firewall/d+. then another update to 5.9.219863.2196 came earlier today and did not fix the high cpu usage as hoped. i started perusing this forum and made a change to the firewall that seems to have fixed the problem. i am sorry i can not provide more specifics as i read so much and did not make note of where i found the information but i think it was in an old thread that related to high cpu usage while running avast with some sort of logging enabled (which i don’t have enabled). i followed the suggestion of one of the posters.
In any case, in my defense+ settings i changed avastsvc.exe from treat as custom to treat as installer or updater and the cpu usage is now back to normal.
i do not know if what i did is the correct solution or is a safe mod. that is why i am posting here. maybe someone can tell me? thanks.
win 7-64 with all updates
avast free 6.0.1367
comodo free 5.9.219863.2196