Open Task Manager in the Processes tab. Click on Memory usage column to sort by memory usage in descendent order and then open Firefox. Look which process uses up memory:

• If firefox.exe, probably you have a issue with the browser. Try to start it under safe mode (here you can find how) and check if Firefox starts up and works as always. If it doesn't, you may have any other problem, for example, you may need to fully uninstall Firefox. Make sure you also delete your profile as stated.

Please keep a backup of your profile. That's where your bookmarks are. See Back up and restore information in Firefox profiles. (You can copy your entire Firefox profile folder somewhere outside of the Mozilla folder.)

Are you able to start Firefox up to the Profile Manager?

Start menu > Run or Search

firefox.exe -p {ENTER}

Click Create Profile, give it a convenient name, accept the default location, and see whether Firefox runs in a clean profile without crashing. You can use this same dialog to switch between profiles.

References:

• Profile Manager - Create, remove or switch Firefox profiles
• Recovering important data from an old profile

Some malware may run when you start Firefox, since it disguises its traffic as browser traffic. You may want to run some supplemental scans. These two tools are highly regarded:

Malwarebytes Anti-malware : http://www.malwarebytes.org/products/malwarebytes_free

SUPERAntiSpyware : http://www.superantispyware.com/

I have this problem too and did a full reninstall + firefox reset (removed cookies and everything). Firefox rapidly increases its vsize and resident memory values (4GB+) until the browser crashes. The explicit allocation stays small the whole time.

I've disabled all addons and extensions and it still happens. What else is there to do?

Edit: I also ran the suggested spyware programs.

Hi duckwilliamson, could you try the following:

(1) Try disabling graphics hardware acceleration.

You usually need to restart Firefox in order for this to take effect, so save all work first (e.g., mail you are composing, online documents you're editing, etc.).

orange Firefox button or classic Tools menu > Options > Advanced

On the "General" mini-tab, uncheck the box for "Use hardware acceleration when available"

If you restart Firefox, is the issue resolved?

(If Firefox is too dysfunctional to change this preference, you can edit a file in your profile folder. However, I don't have the details handy at the moment.)

(2) A standard diagnostic for interference by add-ons is to try Firefox's Safe Mode.

First, I recommend backing up your Firefox settings in case something goes wrong. See Back up and restore information in Firefox profiles. (You can copy your entire Firefox profile folder somewhere outside of the Mozilla folder.)

Next, restart Firefox in Firefox's Safe Mode (Diagnose Firefox issues using Troubleshoot Mode) using

Help > Restart with Add-ons Disabled

In the Safe Mode dialog, do not check any boxes, just click "Continue in Safe Mode."

Any change?

And easier step than creating a new profile for Firefox is to first try Firefox Reset. It's easy, saves your data, and fixes alot of problems with one click. I'd give it a try before anything else

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back to us!

jscher2000, it was the hardware acceleration. As soon as I disabled that firefox runs quite a bit faster and the memory stays level. Thanks! So why is that the problem, do you know? I'm running Win7 x64 with 2xHD5770 Radeon in Crossfire. Is there a place that I should be informing Mozilla about this, or is it known?

Tylerdowner, the posts above state that these steps were already attempted, including the full clean uninstall.

Hmmm, Crossfire. There have been some posts here and elsewhere about a recent driver update that is causing memory and crash issues, but I'm not enough of a hardware person to know what's going on there.

Thank you! That seems to have fixed it quite nicely.

I just thought I would add some background info

If anyone is trying to analyse Firefox's memory usage consider using the inbuilt and interactive tool about:memory instead of something like Windows Task Manager.

• see Firefox uses too much memory or CPU resources - How to fix_memory-troubleshooting-tools
• note work on memory usage, and the tools is ongoing and there is an interesting series of blogs e.g.
  • https://blog.mozilla.org/nnethercote/2012/06/15/memshrinks-1st-birthday/
  • https://blog.mozilla.org/nnethercote/2012/07/11/memshrink-progress-week-55-56/ (per tab memory use)