Add-ons that have not been verified and signed by Mozilla will simply not load. Speaking of add-ons, Firefox 48 also makes extension signing mandatory. In the meantime, the company is asking add-on developers to check whether their add-on will likely be affected and to test it. The intent is to make it the default for all Firefox users in the first half of 2017. As such, Mozilla will be testing multi-process support with add-ons starting in Firefox 49. Multi-processor support breaks some add-ons, especially those that modify content. By separating web content and Firefox UI processes, when a webpage is consuming a large part of your computer’s processor and memory, your tabs, buttons, and menus (hopefully) won’t lock up. Just like other browser vendors have concluded, Mozilla believes using a separate rendering process lays the foundation for significant performance and security improvements in Firefox. To check if you’re in the Electrolysis group, type “about:support” into the URL bar and check to see if it says “1/1 (Enabled by default)” under the Multiprocess Windows line item. In Firefox 48, Mozilla is slowly enabling multi-process support, starting with 1 percent of users, and ramping up to nearly half of the Firefox Release channel.

Firefox Nightly gained multi-process support in November 2014.

In fact, work to make the frontend and add-ons support multiple processes began in early 2013. Mozilla has been building multi-process Firefox support for years as part of the Electrolysis project, and now it’s finally starting to roll it out. The biggest highlight by far is the rollout of multi-process support. In other words, it’s a major platform that web developers target - even in a world increasingly dominated by mobile apps. Mozilla doesn’t break out the exact numbers for Firefox, though the company does say “half a billion people around the world” use the browser.

Firefox for old mac