I have the same question too... from what I understand, since they are both on the same "class" of processor, that means they both have 6 MB L2 Cache, same instruction extensions, etc. That said, the clock frequency what we can use to judge their performance difference. So, 0.1 GHz out of 2.5 GHz is that difference. And, it is merely a 4% improvement. In real life, you shouldn't be able to tell that difference. No? I wonder what's the thought of the others.