What if I have quad 12-core Xeons with 196GB of RAM?
I have a 24-core i9-13900 and 128GB of RAM and I briefly tried it and recall it being what I'd call unusably slow. That being said, I also just discovered that my water cooler's pump has been broken and the poor CPU had been running with zero cooling for the past six months and throttling the bajesus out of itself, so maybe I'd be possible to improve on that a bit.
If you seriously want to try it, I'd just give it a spin. Won't cost you more then the time to download and install it, and you'll know how it performs. And you'll get to try the UI.
I just don't want to give the impression to people that they're gonna be happy with on-CPU performance and then have them be disappointed, hence the qualifiers.
EDIT: Here's a fork designed specifically for the CPU that uses a bunch of other optimizations (like the turbo "do a generation in only a couple iterations" thing, which I understand has some quality tradeoffs) that says that it can get down into practical times for a CPU, just a couple of seconds. It can't do 1024x1024 images, though.