Hi! I've also been having this problem on two different laptops, both Toshiba Satellites! One was a Windows Vista Home Premium whose HDD finally died after the stuttering got really bad and this one running Windows 7 Home Premium. The only constant between both is that I had Avast 4.8 on them. I would hate to think Avast would cause such problems, up to and including the death of a laptop's hard drive.
I love Avast and don't want to change antivirus programs. However, I plan to run Unreal Tournament 2004 on this laptop in the next few months and don't want Avast to cause stuttering in my game.
The poster before me mentioned disabling a "behavioral shield". Which one is that? The services I have listed are: Internet Mail, Instant Messaging, Network Shield, Outlook/Exchange, P2P Shield, Standard Shield, Web Shield.
Also, someone mentioned adding YouTube's URL to a whitelist of sites not to check. Why would this be a bad idea? YouTube is just a video site.
Thanks.