i could be wrong (i'm just a layman) when it comes to these things but i really doubt that there is too much low hanging fruit with AMD64... there is only so much parallelism (ILP) that exists in the code to be exploited. Perhaps someone more informed can correct, but i would think that at some point this means that Intel and AMD are converging to the same core integer performance. Intel has just gotten there faster. i do wonder if that is why despite throwing a lot more transistors at it, single thread performance seems to have tapered off these past few generations for Intel.