Please consider turning on send info to Mozilla before posting a question. This helps us help you. As I have no info from your system that would help see things that cause issues.

We would hope.

It is possible to turn off multiprocessor if you need to. You can always reverse it.

Note : Firefox 57 Quantum release date Nov 14th https://www.mozilla.org/en-US/firefox/quantum/ Note : Legacy Extensions will be disabled and or removed.

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

The only option I had not checked was 'Allow FireFox to Run & Install Studies".

I have now checked that box.

That's weird. SHould have sent info. Just have Allow Firefox to automatically send technical and interaction data to Mozilla, ticked and Allow Firefox to send crash reports to Mozilla, ticked. Leave the Studies off.

Yes, those were the two that were already checked. Have unchecked the Studies.

Pkshadow said

That's weird. SHould have sent info. Just have Allow Firefox to automatically send technical and interaction data to Mozilla, ticked and Allow Firefox to send crash reports to Mozilla, ticked. Leave the Studies off.

You may want to uninstall Firefox and reinstall version 56.0.2 with a Full Version Installer https://www.mozilla.org/firefox/all/ since it did not send info when it should have.

Also it may fix your memory issue.

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

OK - uninstalled FF 56.0.2, rebooted, and reinstalled from the provided site.

I will monitor and advise.

Thank you.

You can try to modify multi-process settings to see if this has effect.

• set dom.ipc.processCount to 1 if it is currently set to a higher value (4)
• disable multi-process windows in Firefox

You can disable multi-process windows in Firefox by setting these prefs to false on the about:config page.

• browser.tabs.remote.autostart = false
• browser.tabs.remote.autostart.2 = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• http://kb.mozillazine.org/about:config

• http://www.ghacks.net/2016/07/22/multi-process-firefox/

Have found that FF still tends to creep up its memory and CPU usage during the day but not as much as before reinstalling.

@cor-el, my system setting was already set to 1 for process count.

I did just now check the box next to 'Use recommended performance settings' and will monitor.

Three days of monitoring the 'Use recommended performance settings' and all appears back to normal.

Have even enabled my add-ons with no change in Memory & CPU usage.

Hello,

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution more easily. Thank you for contacting Mozilla Support.

The solution was for me to select the 'Use recommended performance settings' . This so far has solved the problem.

Pkshadow said

Hello, I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution more easily. Thank you for contacting Mozilla Support.

fyi: Oh, installed the Developer Version last night and it runs really fast.

You need to select that then as the solution Please.