Perhaps the most significant recent iteration of Mozilla's web browser released in the last year was Version 57, going by the name of Firefox Quantum, thanks to a number of overhauls under the hood, including a new Rust-powered CSS engine. Since then, other features have sprung up, such as the option to automatically block autoplaying media and support for Windows 10 dark themes in recent Firefox Nightly builds.
Now, a feature previously brought to other desktop operating systems seems to be on track for a release in Firefox 63. According to Mozilla's Bugzilla tracker, the switch for out-of-process extensions will be activated by default on Linux, which will mean that WebExtensions will then run in their own process from that point onwards, separate from those used for tabs and the browser core. Once enabled, Mozilla expects users to see a general improvement in stability, performance, and security with respect to extensions. This feature made its appearance on Windows back in Firefox 56 last September and later in macOS in Firefox 61 released just over a month ago.
Of course, it should be noted that Mozilla's multi-process efforts in Firefox were a long time in development, with a prototype existing as early as 2009, before ultimately manifesting in a public release in the middle of last year. Despite the expectation that the use of multiple processes would increase memory utilization by up to 20%, Mozilla pushed ahead with a public rollout to boost the stability and security of its browser.
At this stage, Firefox 63 is slated for public release on October 23 this year, according to the Firefox Release Calendar.