Mozilla has announced that it is working on a new Firefox project, which is security-related and called Project Fission. Note that you should not confuse it with Project Fusion, which protects users against existing and future specter attacks, as well as potential vulnerabilities.
As Mozilla did, Google Chrome also called a similar protection Site Isolation, from the previous year. According to Mozilla's announcements, the project will reinforce the first Project Mission by the end of this month and this will include support for out-of-process iframes, which means it will be done in a different process.
What does "Project Fission"Her Mozilla;
Project Fission refers to a renewed process of "Electrolysis" architecture Firefox had adopted 2016 again. As a first step, the "Electrolysis" architecture would only isolate the browser's UI from all web content. Mozilla then triggered an addition of three sandboxes / processes for all five by default: one for the UI and four for the web content. Users were available to modify what content sandboxes they wanted for the Firefox browser. On top of that, Mozilla had said that even if this architecture was not as strict as Chrome, it was an advantage due to the low memory requirements. After all, there are not many times when Chrome has been accused because it uses a lot of memory. However, both Mozilla and Google understood that such architectures are not safe and in a world where CPUs do not come with hardware mitigations against speculative attacks, these projects require user protection.