The problem that I have is that Firefox just slows to an absolute crawl after 30-60 minutes of usage. The rest of the system is really speedy, so the problem is for sure limited to either Firefox or the add-ons. I'm running the latest Firefox (18.0) on Windows 8. I'm running on a brand new clean install of Windows and Firefox at the moment, but I've had the had the same issue on Windows 7 and the last few versions of Firefox. I generally have 1-4 tabs open, and maybe up to 8 if I'm looking at a few things for school. RAM usage (according to task manager) ranges from 250mb at launch to about 600 after an hour or two. The extensions I use are: AdBlock Plus NoScript Ghostery BetterPrivacy DownloadHelper NewTabURL UserAgentSwitcher NoSquint Is there a known issue with any of these add-ons, or is the issue Firefox itself? I've installed Chrome and though I'd prefer to stay with Firefox, the sluggishness is really starting to get to me. I guess I'll just browse with add-ons turned off to check for myself. Just thought someone might have some first-hand experience with an add-on causing similar problems.