Good specs low FPS AC Odyssey

Apr 10, 2018
I have a gtx 1070 TI and an I7 8700k and on Assassins creed Odyssey I get 40-60 FPS on ultra at 1080p yet I see people with the same specs playing on 4K with better results and I’m not sure what’s going on cause I feel like I should be getting better performance but I guess I could be wrong...please help!