Originally Posted by
UALOneKPlus
Really? I use FireFox 3.5 with many many tabs and notice no slow down with Avast.
You may want to check your extensions / add-ons to see if they are causing the slow down.
I installed Microsoft's Security Essentials, and the slowness was even more dramatic. E.g., everytime I would work with a file (like simply deleted an email from my pop3 client) there was a noticeable lag.
So now I'm back to AVG free and so far so good. Faster than either Avast or MS.