Please : go to the Firefox 3 Bar Menu --> Options --> Privacy & Security panel and under Permissions check (put a tick in the box) the setting to Prevent Accessibility Services from accessing your browser.

Monitor in Task Manager. Should stay below 2 gigs. If excessive then do below and monitor and change if need to...Test and go up again , go back down, it will eventually get a zone you and it can live with.

Go to the 3 Bar Menu then Options --> General --> Performance and untick everything. change the recommended size lower then see how it runs. Note: 1 = No Multiprocessor = slow again. Try 2 Restart Firefox after making these changes please.

• https://www.howtogeek.com/332449/whats-new-in-firefox-quantum/

Note : Hardware Acceleration is for Video Card, Monitor to see if remain off or to turn back on.

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

OK, I already had a tick in the box for the setting to Prevent Accessibility Services from accessing your browser.

I am confused by your direction Monitor in Task Manager. Should stay below 2 gigs. What should be below 2 gb - memory?

Under performance I've had this checked - Use recommended performance settings.

When I uncheck Use recommended performance settings, another selection appears called - Use hardware acceleration when available - which is checked, and has a selection called content process limit with a value of 4(default)

Are you saying if I see over 2gb memory used, to leave Use recommended performance settings as unchecked, and to then leave Use hardware acceleration when available as checked, but change content process limit to a value of 3?

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BTW, I just did a restart of firefox, as I Firefox had slowed to non-responsive again, and disk and memory were at 99%.

After restart, I am using only 33% memory (738 MB) and 0% DISK.

After one hour, of little usage was at 45% memory (1,784MB). So I'm almost at 2GB without me opening hardly any new tabs), but still at 1% DISK.

After two hours amd a few more tabs open I'm at 5% CPU, 53% MEMORY (2,300MB) and 1% DISK. (It really seems like as long as DISK % stays low, Firefox is responsive.)

I do see 7 of, what I guess are called sub-processes, running in task manager. Can I just end one of those sub-processes, instead of ending all of them?

I think your FF is corrupted and complete uninstall and reinstall to match your O/S if x86 or x64 and then launch again and see if it fixes the problems. I already know leaving FF57.0.4x64 on for multiple days doesn't kill or eat RAM like what your saying.

I want to clarify, I was not just leaving Firefox on (unattended or unused) while the MEMORY usage went up. I was opening and using some tabs, and scrolling through Facebook.

Right now my FF MEMORY isusing about 3.8GB (73%), but my FF DISK is only 0.1% to 0.4%.

This will liklely allow FF to work fine, until for some reason it starts using DISK up to close to 90%, and that is when FF freezes. Why does FF use such high DISK?

So you are saying to ignore the previous advice about changing the settingsfor Use recommended performance settings as unchecked, and to then leave Use hardware acceleration when available So, you are saying to forget about adjusting the Use recommended performance settings, and - Use hardware acceleration when available settings?

I would reinstall FF if that would help.

Can I export my bookmarks to save them and then import them back into the fresh installation?

Can I save the customizations I've made to the toolbar? (I can't recall where I set some of them up, like the theme I changed. Not a huge deal, just wondering.)

So, you are saying to ignore the advice o try to adjust the settings under Use recommended performance settings and Use hardware acceleration when available