hello, can you try to replicate this behaviour when you launch firefox in safe mode once? if not, maybe an addon is interfering here...

Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Not the original poster, but also had a similar issue of high CPU use Found: - Not resolved by FF safe mode - Not resolved by clearing cache - Found extremely heavy Firefox network socket activity - Found active memory use to be double post-fix when CPU use was high

Appears to potentially be resolved in my case by closing 14 windows containing a total of 471 tabs between them, the vast majority of which were direct links to images that Firefox was happily reloading a dozen at a time to rebuild tab icons from.

Still have three windows open with 247 tabs total between them and no further issues..

The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

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!

problem seems related to code running on certain sites, only a few tabs open at any of my automotive forum sites and off it goes to hog the cpu... the only thing that seems to work is closing the browser, restarting it and opening fewer tabs on the problem sites.