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

https://support.mozilla.org/en-US/kb/firefox-takes-long-time-start-up

https://support.mozilla.org/en-US/kb/quick-fixes-if-your-firefox-slows-down

MemTest LAST UPDATED : 12/04/2020 Could you please run a tool from http://memtest.org/ in order to check the integrity of your RAM?

You will need a thumb or disk drive to install it on.

Do you let Windows handle the page file or did you set a fixed size ? If you use a fixed size for the page file then try the former and let Windows handle the page file.

I have already run memory tests, and also tried changing the paging, with no real affect. Also looking at Task Manager nothing is hogging memory or CPU time.

Just downloaded the latest update to FF 82, and that seemed to help for a while.

Currently typing here, there seems to be no sluggishness at all, but doing so in the currently opened ebay discussion board tab, it is an awful delay at times. I know various browsers, including FF, have had odd issues with ebay, is this just another one? I do not recall earlier versions of FF having this problem.

Is there a website that tests the response time of FF somewhere?

Start Firefox in Safe Mode {web link}

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

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

What is the difference between running FF in Safe Mode and just manually disabling all addons? Does Safe Mode also disable other things that I can somehow check if part of the problem?

In the Safe Mode things do run faster, which of course would be expected, but enabling each addon one at a time and restarting FF, seems to work ok as well, until it just bogs down again.

It would appear that maybe not just one addon is at fault, but possibly a combination of them, unless Safe Mode also disables other things that contribute to the slow down.

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes). If the problem goes away, that tells us one thing. If it does not, that tells us something else.

It could be the work of one of your add-ons, or it could be Hardware Acceleration. How to disable Hardware Acceleration {web link}

Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control> (Mac=<Command>) <Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All Of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is, detective.