About four months ago, we launched multi-process Firefox to a small group of Firefox 48 users. Shortly after the carefully measured roll-out, we increased to approximately 50% of our user base. That included almost every Firefox user not using extensions. Those users have been enjoying the 400% increase in responsiveness and a 700% improvement when web pages are loading.

With Firefox 49 we deployed multi-process Firefox to users with a select set of well tested extensions. Our measurements and user feedback were all positive and so with Firefox 50 we deployed multi-process Firefox to users with a broader set of extensions, those whose authors have marked them as multi-process compatible.

Beyond Firefox 50, we have more work to do to enable multi-process Firefox for users with as yet unsupported extensions. In Firefox 51, if all testing goes according to plan, we’ll be enabling multi-process Firefox for users with extensions that are not explicitly marked as incompatible with multi-process Firefox.

In parallel to work enabling multi-process for more people using Firefox, we’re also working on additional longer term multi-process features that will further improve responsiveness and bring significant security benefits.

The first of those longer term multi-process features is to go from one content process to multiple content processes. The goal is to bring out the most from the multi process architecture, gain performance where it’s possible and minimize the impact of content process crashes. The first step is turning on a second content process in our Nightly channel. That gives us the opportunity to discover and squash bugs as we evaluate the right number of process to ultimately enable. That testing on Nightly is happening now.

The second long term multi-process feature is security sandboxing. Security Sandboxing makes use of child processes as a security boundary. Sandboxing work begins in Firefox 50 with the introduction of our first Windows sandbox. This is an early, laying the groundwork sandbox and is not yet hardened. Over the next few releases, the sandbox will be added to Mac and Linux and will become more restrictive and protective.

Multi-process Firefox has been a big undertaking but it’s already bringing positive results to our users in terms of responsiveness, stability, and security. Stay tuned to this channel for further updates as new multi-process capabilities are developed, tested, and deployed to Firefox users the world over.