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

I did a Refresh and that seems to have solved the issue. Thanks for you help.

That was very good work. Well done. Please flag your last post as Solved Problem so others will know.

After further testing, the refresh did not solve the problem. I tried Safe Mode and am still seeing issues with slowness.

A post was flagged as Solved Problem. If the problem is not solved, please remove that flag. If you don’t, others that can help may not read this post.

Go to that message, and use the Undo link to its right.

Try to update to Firefox 60.0.1 if you are still using Firefox 60.0.

• Help -> About Firefox

I have the same problem with smooth scrolling. I used Firefox 60, Firefox 60.0.1 and Firefox 60.0.2. The problem still occurs. The refresh didn't solve the problem, Safe Mode too . Only Firefox restarts can help, but only for a few minutes. I tried a clean installation but it didn't help either.