Why is this even a thing to talk about? What kind of browser you used that does not have multiprocessing feature? Chrome was built upon it that stops other tabs that is non responsive to affect every other tab. Even Firefox has it now and is improving well. The only limitation is your computer hardware and talking about working on a large project, you are not a ordinary hobbyist. If that's the case you should get a better hardware...
As I said above, even with sandboxing, I can get unresponsive tabs/entire browsers (Firefox & Chrome) plenty (not every day, but several times a month, probably weekly), and not just from crashed tabs but (presumably) desktop heap/browser instability issues.
Running the latest versions of Firefox & Chrome (stable) on Windows 10, x99 board, 6-core 5820k, 16 GB DDR4.