I doubt SSE2 would help much, at most 2x on arithmetic performance. Much time is spent fiddling with arrays, and the newer version of firefox the better that pe

I doubt SSE2 would help much, at most 2x on arithmetic performance. Much time is spent fiddling with arrays, and the newer version of firefox the better that performance is. In addition there are many optimizations to do. A Pentium 1 can decode MP3s in assembly, so in Javascript we probably need a few times more power, but not insanely much more.