They had it before Chrome did, it was in beta 1. No one uses IE that knows better, so no one knew about it till Chrome came out. Then they tested other browser's and then thats when people found out about it. I wonder why Microsoft didn't talk about this, would of been a big thing for them.
I hope that it doesn't happen. I stress my CPU enough on my own. I think it would be an intelligent choice for the FF people not to do this. I haven't tried chrome because, there isn't a Linux version yet. I can imagine that the "own process" you speak of will be enough to cause me not to like it. I have open atm, 2 browsers,( FF and Opera) and occasionally, Seamonkey too, a file broswser, 3 terminals( 1 running screen for an effective 6 terminals), bluefish, and a time tracker. All this costs at 10 - 20% CPU usage. I don't need Google taking CPU cycles by it's own choice.
I'd say I wouldn't have a choice. If IE/Chrome already does it, it's only a matter of time before Firefox/Opera get on the bandwagon. I love FF, and have been happy with it for nearly two years now, so I'll be sticking with it for a while.