Chrome was built from scratch around this concept. Firefox wasn't, and there's a whole wealth of infrastructure around the non-multiprocess approach, from the

Chrome was built from scratch around this concept. Firefox wasn't, and there's a whole wealth of infrastructure around the non-multiprocess approach, from the way plugins work, all the way on up. Migrating towards multi-process has been a decidedly non-trivial task for Mozilla, involving a lot of effort from a lot of people.