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

• set number of content processes to 1 if it is currently set to a higher value (4)
  Options/Preferences -> General -> Performance
  remove checkmark: [ ] "Use recommended performance settings"
  https://support.mozilla.org/en-US/kb/performance-settings
• disable multi-process windows in Firefox

You can disable multi-process windows in Firefox 58+ by setting this pref to false on the about:config page.

• browser.tabs.remote.autostart = false

Note that disabling multi-process causes Firefox to crash when a tab crashes, so if you regularly experience crashes it is best to leave multi-process enabled.

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

I really do appreciate that you took the time to answer. However, my machine is fairly up to date, I can game MMOs for hours without any issue whatsoever, etc, so excuse me if I find that the new firefox is going backwards users friendly wise - aka disabling functionalities translates fail in my book. Thank you though ...

MMO games doesn't use Browser so this is a false equivalence being used here. Did you backup your bookmarks and completely uninstall FF and delete Mozilla folder in either Program files locations? Then redo a reinstall of FF that matches your O/S bit version aka 64O/S to 64FF and then see if the problem is still there. This is what I had to do to fix my upgrade when I went to FF57+. Machine up to date doesn't tell us much here.

Yes I am aware that machine up to date doesn't say much XD & I mentioned MMOs as a fair example for it. I am a computer noob thus not familiar with specs and such. I did uninstall FF completely a while ago, but I can definitely do it again to see if this time it helps. Thank you WestEnd.

Hi, sorry having issues : Please follow what cor-el suggested re the cores being used : Please go to Options --> General --> Performance and uncheck the box for Use Recommended Settings and try changing the Process count to 2 and can also go up but note more cpu and ram will be used. You will need to reboot after makng any changes.

Also please check this : Then go to Privacy & Security and down to Permissions. Please ensure that the box for Prevent Accessibility Services from accessing your browser is checked.

You can uninstall/reinstall this way for the best results : Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove your Firefox program files and then reinstall Firefox. This process does not remove your Firefox profile data (such as bookmarks and passwords), since that information is stored in a different location.

To do a clean reinstall of Firefox, please follow these steps: Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from this page) and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (or open the Firefox menu and click the close button ).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here.

WARNING: Do not use a third party uninstaller as part of this process. Doing so could permanently delete your Firefox profile data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be easily recovered unless they have been backed up to an external device! See Back up and restore information in Firefox profiles.

Please report back to say if this helped you!

Thank you.