Firefox 55.0.3 started using >100% CPU.(Mac)

User Help for Mozilla Firefox

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Joined: October 19th, 2007, 5:19 pm

Post Posted October 28th, 2017, 7:46 pm

bluloo wrote:So, I did a FF refresh, it re-imported my bookmarks etc, and I then reinstalled 6 extensions so far, and have a hundred tabs+ opened. FF is at ~10% CPU.

Does that mean something was corrupted, and does it indicate what that might have been?

Appreciate the responses, BTW! :)

You originally stated that you had 12 extensions, and so far you have re-installed 6 of them (all seems good). There is a good chance that one (or more) of the remaining 6 extensions was causing problems. If you plan to re-install those other 6 extensions do so one at a time and then test. This will help you isolate things (although you did do a FF refresh, so that is part of the mix as well).


User avatar
Posts: 908
Joined: October 19th, 2007, 5:19 pm

Post Posted October 28th, 2017, 8:29 pm

langdonb wrote:BTW, I run FF on my laptop using "portable Firefox". So I deleted that app and reloaded with a version on my back up from a month ago and it seems to be running OK...

What version of Firefox did you re-install from your back-up? The reason I ask is that if you are going to do a fresh install on the iMac you probably want both versions of Firefox to be the same.

Moving forward (below), I am assuming you are going to do a fresh install with the latest release version (56.0.2)

langdonb wrote:I do want to move forward with installing a fresh version on the iMac and be able to synch with the laptop

Here is all you have to do to have a brand new fresh install:

[0] Open your current version of Firefox and export your bookmarks to the Desktop (precautionary measure)
[1] Download the latest stable release to your Desktop
[2] Go into the Applications folder and move to the Trash
[3] Go to ~/Library/Application Support/ and move BOTH the Firefox folder AND the Mozilla folder to the trash
[4] Go to ~/Library/Caches/ and move the Firefox folder to the Trash
[5] Go to ~/Library/Preferences/ and move org.mozilla.firefox.plist to the Trash
Everything on your Mac related to Firefox is now in the Trash. ***** DO NOT EMPTY THE TRASH UNTIL EVERYTHING IS RUNNING WELL *****
[6] Open the latest stable release .dmg on your Desktop (from step 1) and install Firefox as directed.
[7] Open Firefox, set your prefs, and re-import your bookmarks from the Desktop

You now have a TOTALLY CLEAN install.

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