Eventual CMYK support was announced back when I had hair. Today I'm pretty sure that CMYK still isn't supported, though I think there might have been some recent advances in that area. Non-destructive editing was supposed to also become a thing with GEGL, but that never really materialized.
I needed this the other day. CMYK output is in the 2.99.xx nightly builds and works fine. Export only, can’t work in cmyk natively.
So it took 27 years to add CMYK support? Well there is progress I guess.
It's in nightly, so it might be in prod 5 years from now :-)
I have a 2 year old desktop apple computer and GIMP gets about 2 fps for simple tasks like using the pencil to draw. (maybe it's better on linux or PC)
It's, sadly, a LOT faster on a Windows machine. Performance (especially boot times) is horrid on even more powerful Macs (M1Pro f.ex).