Please uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved.

Reinstall with Current Release Firefox 57.0 with a Full Version Installer https://www.mozilla.org/firefox/all/

https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration TRY NO HARDWARE ACCELERATION Most issues are caused by out dated and corrupted drivers. If do not know what your card is : GPU-Z will tell you this https://www.techpowerup.com/gpuz/

FIREFOX TO SLOW

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

https://support.mozilla.org/kb/Firefox+is+already+running+but+is+not+responding

https://support.mozilla.org/en-US/kb/firefox-slow-how-make-it-faster

https://support.mozilla.org/en-US/kb/firefox-uses-too-many-cpu-resources-how-fix

https://support.mozilla.org/en-US/kb/firefox-uses-too-much-memory-ram

https://support.mozilla.org/en-US/kb/firefox-hangs-or-not-responding

Please let us know if this solved your issue or if need further assistance.

I did all of the above. Still hangs and freezes.

thanks for reporting this. could you go to the firefox menu ≡ > help ? > troubleshooting information, copy the contents of that page and paste them here into a reply on the forum (or if it's to long through a site like https://pastebin.mozilla.org/ and provide the link here)?

this might give us a clue what is going on. thank you!

https://pastebin.mozilla.org/9073018

great, please try the following which should hopefully take care of this lag: go to the firefox menu ≡ > options > privacy & security panel and under permissions check the setting to prevent accessibility services from accessing your browser.

That did it I think! Oh my gosh, I'm so appreciative. I'll see if it is still working tomorrow and thene "solved the problem" click. Already it is amazing I can type this to you in Firefox!

TwinsMomVA said

After the update yesterday to Firefox Quantum, I can no longer use Firefox on my desktop. It is slow, it hangs and then freezes. I've tried everything in the troubleshooting section (profiles, drivers, refresh, fresh install, everything.) I am posting this message from...gasp...Microsoft Edge. I really hope there is someone who can help me, I really don't want to have to leave Firefox!

TwinsMomVA said

After the update yesterday to Firefox Quantum, I can no longer use Firefox on my desktop. It is slow, it hangs and then freezes. I've tried everything in the troubleshooting section (profiles, drivers, refresh, fresh install, everything.) I am posting this message from...gasp...Microsoft Edge. I really hope there is someone who can help me, I really don't want to have to leave Firefox!

great, please try the following which should hopefully take care of this lag: go to the firefox menu ≡ > options > privacy & security panel and under permissions check the setting to prevent accessibility services from accessing your browser.

This worked for me! Thank you!

can't find where this box to check is on windows 8.