> Browsers that use several child processes (like IE, Chrome, Safari/WebKit2) are faster, have less latency, crashes involve only one tab and the child processes run with limited OS priviledges ("sandbox") than browsers with only one process (Firefox, Safari/WebKit1).
It's more complicated than that. For one thing, "have less latency" is often the opposite: a keypress in a multiprocess browser has to travel from the user-facing process to the child process, then the effects have to travel back. In a single-process browser, there is no need to cross that boundary back and forth. You can see this in action in games for example, where you can sometimes see more input lag in multiprocess browsers.
Regarding speed, depends how you define it. Definitely multiprocess gives you responsiveness - one slow tab doesn't slow down the others. But throughput, not necessarily.
Overall though, multiprocess is a good thing. I'm just saying it isn't a win across the board, like everything it has downsides.