What would you do with more CPU cores? One for the UI; one for CPU-only filters (if there are such a thing) and various other background workers like network downloads.

Everything else—the rendering, scaling, compositing, etc.—runs on the GPU, not the CPU, where it uses hundreds of cores. Y’know, like a 3D game.

And, like a 3D game, it’s still slow, because it’s doing something genuinely hard and your powerful GPU still isn’t powerful enough.

Answering this question means you have to understand a bit about how computers work. More cores doesn't automatically translate to faster performance. Photoshop is lightly threaded for most operations.

A cursory search brought up this link, but you should read up on threads and the difference between CPUs and GPUs:

https://macperformanceguide.com/blog/2017/20171223_2311-why-...

These are things that are processed better by a smaller number of more powerful cores than a larger quantity of cores.

Multiple cores are really good at handling a lot of smaller processes. Photoshop just has a couple really heavy individual processes.