Try the Firefox Safe Mode to see how it works there. The Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• You can open the Firefox 4.0+ Safe Mode by holding the Shift key when you use the Firefox desktop or Start menu shortcut.
• Or use the Help menu item and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Don't select anything right now, just use "'Start in Safe Mode" To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before using the Firefox shortcut (without the Shift key) to open it again. If it is good in the Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one.

Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

I've been experiencing this problem for over a week now in FF 18 & 19. I have Firefox set to "Show my windows and tabs from last time" on startup. The problem usually, but not always, occurs at startup. And it usually, but not always, occurs with Google sites (mail, drive, etc.).

I've tried a number of things with no effect:

• Safe mode / Disabled add-ons
• Reviewed/updated plug-ins
• Cleared cache and cookies, and network cache
• Reset FF completely

Firefox can perform fine for an hours-long session, but when I exit FF and relaunch, it hangs. I have no recourse but to use Windows Task Manager to stop FF. Sometimes the problem will recur on next launch, and I have to repeat the "stop process/relaunch" or reboot.

Whenever I resort to stopping the process, I've noticed Firefox is consuming a considerable amount of memory -- upwards of 275K or even 350K.