This question already has an answer here:
Having seen various people test powerful emulators on their computers, I have come to surprise hearing about how one CPU can have triple the clock speed but still have worse single-threaded performance; or how one CPU can use 16 threads but one forced to use a single-thread can wipe the floor using 1 thread and tons of rapid context switching, even assuming a multi-threaded app.
Some of the best Intel CPUs can be as underclocked as much as possible and still run very demanding programs perfectly, and some of those Atom CPUs can be overclocked as much as possible and still not run them without chopping/lags, etc. Here's what I've noticed:
A 1.5 GHz Intel i7 5960x can run latest Photoshop and Adobe After Effects, including PS2/GameCube/Wii emulators and games fullspeed; an overclocked Celeron 450 @ 3.3 GHz can barely do the same, and it's technically more than twice as high in clock speed.
Also, a 4 GHz Atom N270 seems to perform worse than a 1 GHz i7 5960x. Why is this?
With these really new and expensive Intel CPUs, clock speed seems to mean very little, as they can be 1.9 GHz and run everything, whereas some 3/4/5+ GHz CPUs of yesteryears can't even.
So fast that even forced to use a single core while another CPU uses multi-core, they can do better.