So how can we make processors perform better if we cannot make them go faster? The answer, in principle, is "use parallelism". So we get to a world where we have 2, 4, 8, 64 cores in a single processor chip: in effect we have 2, 4, 8, 64 more or less independent processors. There may be more of them but they are running slower so they don't generate as much heat. Great for hardware manufactures, but not very good for users. Well it is probably good for high performance computing people and large server people since they have been playing the parallelism game for a number of years. But it is not good for end users. Why is this? Their applications are going to run slower because the processor running their application is running slower.

The software that most people use are web browsers, word processors and, possibly, spreadsheets. These software products have been implemented for execution on single processor systems. They may use multithreading, but underneath there is generally an assumption of a single processor and multitasking. If they can use the real parallelism on offer with multicore systems, it is probably by fluke and not by design. The point is that the software that used to run on single processors that got faster and faster is now running on multicore processors that are running slower.