Firefox 49 will ship with multi-process architecture

Mozilla plans to make Firefox 49 the first stable version of the web browser in which the browser’s new multi-process architecture Electrolysis (E10S) is enabled by default for a major part of the browser’s userbase.

It seems that the never ending story of making Firefox a multi-process browser will soon come to an end, as plans are underway to deliver the feature to the stable version of the browser with the coming two releases.

Firefox E10S is Mozilla’s largest undertaking up until now, if you leave out the creation of Firefox in first place, and that’s probably one of the major reasons why the implementation was plagued with delays.

It all started in 2013 when Mozilla announced that it would revive the multi-process project for Firefox, but it took about a year before it made the project a priority.

Mozilla wanted to deliver E10s as early as Firefox 36, but things got delayed along the way and it was clear that it would take longer than expected to deliver the new feature to the stable version of the browser.

firefox multi process

The Firefox E10S Story starts with Firefox 48

Firefox E10s met all release criteria in the last six weeks during beta tests including stability, page loading times, startup and shutdown times, memory use, and more.

The current — and likely final — schedule for multi-process Firefox is therefore:

  • Firefox 48 Stable: about 1% of qualifying users will have the multi-process architecture enabled by default. Mozilla plans to increase the number during the release cycle.
  • Firefox 49 Stable: 100% of qualifying users will be able to use E10S.

Qualifying users are all users that don’t use add-ons and have not activated accessibility support over 30 days.

The groups that will have to wait a bit for E10S account for about half of our release users and include Windows XP users, users with screen readers, RTL users, and the largest group, extension users.)

Firefox 48 will be released on August 1, 2016, and Firefox 49, on September 12, 2016.

Mozilla revealed in January that 40% of Firefox users don’t use add-ons. If you add Windows XP users to that, and those who have used accessibility tools, you’ll probably come close to the 50% of users that Asa Dotzler mentioned recently when he revealed the schedule.

This means that the major part of the “close-to” 50% will get E10S with Firefox 48, or at the latest with Firefox 49, and that the remaining percent won’t get it with Firefox 49 but at a later point in time.

Not all add-ons are compatible with E10S, and while major ones are already, others are not right now and some will never be compatible (for example abandoned add-ons).

Launching E10S only for users without add-ons ensures that add-on compatibility issues won’t play a role when it comes to the release.

Mozilla announced that it will monitor the launch carefully, and there is still a chance that the final release will be postponed if major bugs are discovered in the process.

Firefox Electrolysis is already on by default on the Nightly and Developer channel. 50% of qualifying beta users got E10S with Firefox 47 Beta, and 100% will get it with today’s update to Firefox 48 Beta.

Now You: Have you tried Electrolysis already? What’s your experience so far?