For anyone interested (and using an M1/M2 Mac), whilst Amazing AI offers limited twiddling (just the step count and seed) it is native Apple Silicon, comparatively light on resources, and on my base model 2021 Air (8GB RAM, 7 GPU) it produces a 2048x2048 pixel 100 iteration image in under 5 minutes.
I know that headline number is slow compared to machines with beefy specs, but remember that this is 100 iterations on the lowest power M1 you can get, with 16 times the pixel count of the online 512x512 ones. And even with 40 iterations you can generate some stunning images with the right prompts.
Draw Things has a massive amount of configuration, is equally fast (it's also native) and can do a variety of output sizes.
Haven't noticed anything, but TBH I also haven't looked as I've had no need to question things - the rest of the OS runs fine alongside, with dozens of browser tabs, plus both Amazing AI and Draw Things running (though only one actually generating at once). And with about 50 iterations I'm losing around 1% battery every couple of images so it doesn't seem particularly taxing, whilst running cold.
Edit: It isn't obvious with Amazing AI but it may in fact be doing what Draw Things makes explicit in the options, which is generate at 512x512 and use your choice of upscaler to get to 2048x2048.
I know that headline number is slow compared to machines with beefy specs, but remember that this is 100 iterations on the lowest power M1 you can get, with 16 times the pixel count of the online 512x512 ones. And even with 40 iterations you can generate some stunning images with the right prompts.
Draw Things has a massive amount of configuration, is equally fast (it's also native) and can do a variety of output sizes.
Both are free from the Mac App Store.