Mozilla’s Project Fission to run cross-origin iframes in separate content processes is now available for testing in Firefox 70 Nightly. We’ve written instructions on how to enable Fission in Firefox, but at that time, Mozilla officially hasn’t acknowledged the feature is ready for testing, now it is.
Google Chrome already has Site Isolation feature available and integrated into the browser. This has been done after Spectre and Meltdown attacks were discovered. Mozilla too keen on bringing the full site isolation feature to Firefox browser, the company has announced about the Project Fission in February 2019 in regards to that.
In the second newsletter of Fission, the company notes “It’s now possible to turn on Fission in Nightly builds of Firefox by setting fission. autostart pref to true.”
Mozilla’s Lika Nayzell who works on Site isolation says “When Fission is enabled, each cross-site iframe is loaded in the different content process, meaning lots of different processes participate in drawing a single tab.”
For a fission-enabled tab, Firefox shows a tooltip with message [F ..] followed by a number of process IDs when you hover over, check the example screenshot given below.
As Fission still has a lot of stability issues, Mozilla suggests not to use the feature in a working environment.
Without any ado, here is how you can turn on Fission in Firefox Nightly if you want to test the feature right away
1. Visit about:config
2. Search for “fission”, click on toggle button for the “fission.autostart” pref to change its value to “true”.