Nowadays the clock of CPU means basically nothing, any 2.0ghz core i5 is ways faster than a 3.6ghz P4.
The are many ways to improve the performance of a CPU like optimizing its pipeline or adding more cores.
Increasing the clock is just an old and dated way make a faster CPU which usually leads to cooling problems.
Also since the day I saw the console I knew that it wasn't going to have high clock because of the small the size of its box.
Finally, demanding games need a fast GPU not a fast CPU.








