|== Process Separation (electrolysis, or e10s) ==
|As of ff-48 this is available - it will apparently be turned on for some binary downloads and might become the default. But for source builds it defaults to off. To see if it is enabled, look at about:support and check for a '1' in "Multiprocess Windows".
|To turn that on, go to "about:config" and set browser.tabs.remote.autostart to true, then restart firefox.
|If about:support now shows it is on, fine, but for me (ken) it shows 'Disabled by add-ons' (I only have Adblock Plus and Privacy Badger). Forcing it on for testing is officially discouraged, but a comment at lwn.net said it now works well when forced.
|To do that, go to about:config, right-click anywhere and choose 'new' th en 'boolean', set the name to browser.tabs.remote.force-enable and set that to true. I suppose it is necessary to restart firefox after that.
|Personally, I have no idea if this does anything useful, but I'm a tester and so I'll give it a try!