Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

• Don't make any changes on the Safe mode start window.

See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

If it does work in Safe-mode then disable all your extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

I installed the latest version of FF a few weeks ago (v. 8.0), created a totally new profile, eliminated extensions, and I still get this issue - primarily with Gmail.

Like others have mentioned, if left open over night, FF is unusable in the morning.

FF becomes unusable within a few hours of use, even if I have but few windows open. Typically, FF is the only application I have running since I use Google Docs and Gmail now. I started using Gmail so I could stop running Outlook - goodness I miss the functionality. I thought eliminating one memory hog would allow the other hog to flourish. Not so.

I created a new clean Windows profile and tired again, but FF continues to be very slow. It opens slow. It runs slow. It crashes often. It becomes unresponsive even more often.

Too many things are simply not compatible with Chrome yet. But it seems over the years FF has developed all the issues that drove me to it from IE to begin with.

Version 3 was supposed to fix the issues. Then 3.1. Then 7. Now 8.0 and although some nice features have been added, the basics are still not working well. I use my browser all day every day - sometimes for 15-16 hours a day.

I have FF 8 on a second computer, and went through the same steps with it. It has all the same issues.

I long for fast and lean and good memory management. I know the browsing world has become more complex - sort of like the transition from manual to automatic transmissions. But the gears on this box are grinding.