Starting Firefox 68, you won’t be able to turn off Electrolysis or e10s (Multi-Process Firefox) and switch to the non-e10s mode (single -process Firefox) by using hidden pref, the support for the pref “browser.tabs.remote.autostart” has been removed and will be ignored even if you set pref value to false.

Mozilla made changes to future Firefox version where visiting about:config and changing pref ” browser.tabs.remote.autostart” value to false simply won’t disable e10s and further more, support for force-disable and force-enable e10s prefs has been removed as well, this applies if you’re running official Firefox builds and not running automated tests for debugging.

Mozilla’s Gijs Kruitbosch says in a “changes to turning off e10s “thread that Firefox users shouldn’t be running non-e10s configuration regularly and says it is less secure. He confirms the autostart pref will continue to work on

• non-desktop Firefox versions (Fennec),
• local builds and for automation tests.

If developers want to disable e10s on official builds for testing they can use MOZ_FORCE_DISABLE_E10S environment variable. Do know running Firefox with the multi-process feature disabled has side effects as well, for instance, doing so, breaks activity steam or New Tab Page, this is one of the reasons for this move also.

Key takeaways

• In Firefox 68, visiting about:config and toggling browser.tabs.remote.autostart pref has no effect on e10s
• Eventually, the above pref as well as browser.tabs.remote.force-enable and browser.tabs.remote.force-disable will be removed and stop working.
• Your Firefox will be running with Multiple processes unless you’re using unofficial builds or set environment variable.

Has this change bothered you? What’s your take on MultiProcess Firefox as it brings stability, security and performance improvements to the table. FYI, recently, with more confidence, the company has increased the number of default content processes to 8 from 6.