Interestingly the system hang problem which some users (me included) experience with some websites appears to be fixed in FF 23. That was my first observation, my second was could it be that it was the Avast script shield that was causing the problem?
I personally wasn’t/haven’t been experiencing any hang time in FF.
Website hangs can be caused by many different things as I’m sure you are aware; limited RAM being one of the main culprits.
Can’t say for sure about Script Shield. 
Script Shield doesn’t seem to be working in Opera and in Mozillas’s SeaMonkey. Details here:
http://forum.avast.com/index.php?topic=131605.0
@RejZoR, if the other shields do the job, as you menioned in Reply#15, shouldn’t we just uninstall Script Shield?
Or what does Script Shield do special when it works?
Script Shield does additional analysis of scripts on runtime, but in general Web Shield checks the .js files before they enter browser and Network Shield checks their URL. And File System Shield also checks the files.
So if I use my own .VBS script, or someone gives me one, will ScriptShield check it as well in addition to files shield and behavior? Or if some .pdf file has scripts in it will the other shields check it?
Not working for me either.
Just updated to FF 23 and Script Shield isn’t working for me either.
I believe that in a case as this ,one the team of avast should do a bulletin and explain when approximately the patch will be available ;D
istalled version 8.0.1496 beta r3 and script shield in firefox 23 ok
Are they even aware of this problem.
http://forum.avast.com/index.php?topic=131804.0 version beta fixit the problem