Certainly, but many "wasteful" operations are reading/writing main memory unnecessarily - and since a single trip out to memory and back can take many many CPU

Certainly, but many "wasteful" operations are reading/writing main memory unnecessarily - and since a single trip out to memory and back can take many many CPU cycles, typically optimizing memory access time does more for "bad code" than optimizing the number of CPU cycles per second. But obviously, you're right too - faster is faster after all :)