Hi  !

Did you do this  :

Type in the address bar about:config   (press Enter) (promise to be careful, if asked)

Type and search for the preferences :

browser.tabs.remote.autostart and set it's value to false (default)

browser.tabs.remote.autostart.2 and set it's value to false

Then close and restart Firefox.

Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

OK, I finally realized I was entering about:support not about:config. Big difference. Got it changed, now I'll see if it helps performance.

Note that you can also experiment with the number of content processes.

• Options/Preferences -> General: Performance
  remove checkmark: [ ] "Use recommended performance settings"
• https://support.mozilla.org/en-US/kb/performance-settings

What kind of performance issues do you have?

Did you try Firefox Safe Mode?

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

You can create a new profile to test if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Now that I have e10s set to false, it seems to be better.