Hi. Ive got the exact same problem. Firstly i played this game in my ps4 pro but when i saw how it performs I ran to the store and bought a brand new xbox one x. The game runs better and in native 4k of course but it still is not smooth. I have tried everything with my tv and xbox settings. I have slight stuttering almost all the time during day (when theres a lot of shadows and daylight). At night or during a storm the game is 100% smooth. My frames drop even more in valentine. in some buildings my frames drop to 20 fps, heavy stuttering. I am glad that im not alone here, because I also thought that my tv or new console is faulty. I doubt its the cable because in other xbox games that are also 30fps and 4k, the gameplay is 100% smooth (forza horizon 4 for example). I think the only solution is that R* patches the game because my eyes rally hurt me after a while. I have spoken with the support 5 times already and noone seemed to have an answer, so i really think its jus the game itself. I am really mad that so polished game was released this way and noone cared that it runs crappy on a frekin x box one x!!! Btw. I disabled DVR recording in my xbox and i think it helped a bit... you may try it.