This workflow is for generating hyper-detailed 4k wallpaper-sized images. On my 4090, it can generate images in about 45 seconds. It hasn't been tested on cards with less than 24 gigs, but I'd be curious if it works (maybe swapping out some of the other VAE encode/decode nodes with tiling ones and adjusting the tile size down may help).
Edit: Confirmed working on an 11GB 2080Ti.