Actually, not quite - it uses UIWebView, which doesn't have some of Mobile Safari's JavaScript improvements, so no matter how hard it tries it won't quite be able to keep up.
you don't actually need insanely fast JS to load most web sites. i agree you'd need it for something highly interactive and intensive, but again not most websites.
I actually find the difference noticeable when using Chrome on iOS. Only Safari can JIT Javascript for instance. At least with Chrome it also seems to run out of memory faster (it has access to less?).