Firefox becomes slower after long periods of browsing

Question

Firefox runs great at first but gradually becomes less responsive over time. A temporary fix to this issue is simply restarting firefox (close FF then re-open FF), but this gets quite annoying. Firefox runs fast, then gradually I notice it become slower and slower until I restart the application. Then the process repeats.
Some issues I begin to see after 2 hours of browsing:
1. slow response to scrolling. 0.5-1.5second delay after input, it scrolls.
2. delayed typing. I type something in the search bar and it takes 0.5-1.5 seconds for the individual letters to show up on the search bar.
3. Random lock ups
Reinstalling Firefox (including deleting my profile folder), clearing temporary and history files has no effect.
I'm running 3.6.12 and I have the following add-ons:
Ad Block Plus 1.3.1
Download Statusbar 0.9.7.2
Google Toolbar 7.1.20100830W
Java Console 6.0.22
McAfee SiteAdvisor 3.2
Password Exporter 1.2.1

Answer 1

At this point I think you should get Applejack...
http://www.versiontracker.com/dyn/moreinfo/macosx/19596
After installing, reboot holding down CMD+s, then when the prompt shows, type in...
applejack AUTO
Then let it do all 5 of it's things.
At least it'll eliminate some questions if it doesn't fix it.
The 5 things it does are...
Correct any Disk problems.
Repair Permissions.
Clear out Cache Files.
Repair/check several plist files.
Dump the VM files for a fresh start.