It is for lack of a better word less smart of a processor, with literally hundreds of millions less circuits inside, all of this makes it do less work per MHZ, heck you look for a little older processor you can see they were up over 3ghz a long time ago, but new processors could be downclocked to about 1.0 ghz and still beat them performance wise. They've just generally figured out how to make them tick better, If I fully knew all the answers to the "how" then Amd would want to hire me to catch up to intel 😛