For a browser, that's not really possible without a significant team of over-the-average and paid developers. There are a lot of complexities in a browser. It has to have its own GPU driver, JIT compiler, optimized scheduler to pull page components, another scheduler to run JS, a cross-platform rendering abstraction, hacks for 30+ years of WWW. All of that should be fast. Because everything else is extremely slow and wasteful on Web.

People who can handle this complexity are extremely mobile in the industry. They can always find employment in a much better paying place than Mozilla. And a competitive browser has to have such developers on generous payroll.

One of the issues with Firefox is its codebase. Some parts of it are slowly rotting and it has its own fair share of 20-year-old bugs. Mozilla is slowly failing to keep up with the ever changing landscape and dealing with the age of their codebase. There is a reason why Electron could be developed with Chromium but not Firefox. Mozilla really tried this as well, it just didn't work.

If you're forking, Chromium or Safari are a better start point than Firefox.

[dead]