Sure, it depends. I've seen embarrassingly parallel (yeah, that's a real term) code with speedups in the 20's. My personal best was a 9x speedup, partly by usi

Sure, it depends. I've seen embarrassingly parallel (yeah, that's a real term) code with speedups in the 20's. My personal best was a 9x speedup, partly by using SSSE3 and partly by some really good prefetching and non-temporal writes. If you look at what I said in the very narrowest light, I agree that SSE2 all by itself typically delivers a 2x speedup per core over non-SSE code.