lol why do people keep saying 30-40 fps is playable in non-fps games. It's unplayable in pretty much every game in which your character moves. Witcher 3 is an action rpg, any dynamic scenes, including fighting, at 40 fps is an absolute casserole of nonsense on the screen. I personally play @1440p high graphics/high postprocessing, fps hovering around 115.
4K is nice for taking screenshots or video capture, but actually playing 200 hrs at 40 fps is just awful.