Required denoise processing power

Yes, it’s all done in the graphics hardware, with an extra boost if machine learning acceleration hardware is available, because AI Denoise is based on machine learning. Unfortunately, that means a lot of hardware that’s only a few years old is not well optimized for this type of work.

In short (this is what all the posted links will tell you), you might get the time down to one minute per image or below, by using a recent Windows laptop with a discrete GPU, or a Mac with an M2 processor. If you spend more money, you might get the time down to under 20 seconds per image if you buy a Windows desktop that has the type of Nvidia graphics card D Fosse recommends, or an Apple Silicon Mac with the M2 Max or M2 Ultra processor.

AI Denoise doesn’t need an excessive amount of memory or CPU cores, but it does work best when it isn’t starved of those resources. So generally, the base model of a PC or Mac is not going to be ideal, you’ll want at least 16GB of memory and it’s probably a good idea if the CPU has more than 4 cores.

https://community.adobe.com/t5/forums/searchpage/tab/message?advanced=false&allow_punctuation=false&q=denoise%20slow

This runs entirely in the GPU (graphics card). It doesn't touch the CPU (main processor).

To get decent performance from Denoise, you need a fairly new GPU like the Nvidia RTX 30- series or 40- series. Then you'll se timings from 10 seconds to half a minute or so, depending on file size and model number.

Laptops are inherently problematic because they all come with dual GPUs these days. That tends to cause conflicts, and you may need to completely disable the integrated GPU.