I have a early 2013 retina MBP and I have had horrible UI lag since I got it (Mavericks was the worst OS for UI lag, Yosemite helped a little, El Capitan helped a lot). How do the iMacs compare?
Also, how horrible do games look under Windows when running games at 1080p?
Also, how horrible do games look under Windows when running games at 1080p?