… With WinXP SP3 … I finally did not have any particular issue since v2011 (currently the only problem I have is some random BSOD when enterng SafeZone! not too bad!) … nevertheless I had to modify other things on the machine to make AIS v9 not cause me issues that made the PC unusable! I feel the code is getting finally mature (we are approaching February … usual Avast release date, before commercially decided to squeeze it to October! :-X )
Remember you can always do the trick with WebShield.ini to basically restore v8 behaviour… it seems to work! 
I am preparing another topic explaining what I had to modify on the machine to make AIS v9 (but it applies to all the versions, I feel) run without freezing every other mouse click … maybe it will help someone of the guys that have still issues… :