Recently Firefox said they were moving away from threads to processes. I think that's a mistake. Killing Chrome was a pain at times because when it does hang all the child processes had to be killed independently. It was possible to restart Chrome with orphaned processes. What a mess.
Also, I like the implementation of profiles in Firefox much better. I have a different profile for work, home and various side jobs. Very nice.
Chrome developers are crap developers and they hide behind processes because they don't have the chops to do threads. I hate to see Firefox move in that direction. Maybe Firefox needs to since Firefox is adopting Chrome extensions. But I refuse to use Chrome because it has crappy performance and usability. Hopefully Firefox doesn't move in the same direction.