One interesting aspect of how Mozilla is implementing multiprocess is they are not dedicating one process per tab.
Right now teams are working to define a fixed number of processes for future rollouts. The question is whether new versions will coalesce pages randomly into a fixed number of processes or coalesce pages by domain.
“We can learn from the competition,” said Dotzler. “The way [Chrome] implemented multi-process is RAM-intensive, it can get out of hand. We are learning from them and building an architecture that doesn’t eat all your RAM.”