PC processors entered the Gigahertz era today in the year 2000 with AMD's Athlon — AMD hit marketing gold with its 1 GHz Athlon, beat Intel by a nose

Consumer PCs have long abandoned the multi-GHz race for core count and NPU inflation.

Tom's Hardware
Isnt it that at some point the GHz just aren’t useful anymore or rather not physically possible. I think they abandoned it for a good reason.

You get rate limited by cache. The literal physical distance between cache(3) (tiny ram(s) in the processor) and processor can’t be zero. So those signals must travel over a distance at the speed of conduction. Having multiple processors allows tasks to be done simultaneously, effectively multiplying processing speed.

But more speed is particularly useful with bad/legacy software(single thread). SolidWorks is a good example.