Exactly the same problem here. Game runs at a solid 60fps (VSync on) for usually 30 mins or so, then for whatever reason it'll drop to 52fps and get choppy. Choppiness persists when moving the cursor around the map or menus. Switching character doesnt help, nor does changing graphics settings or enabling/disabling vsync through the gpu. The only (temporary) fix is to exit to desktop and reload the game. Then it'll run perfectly for another 30 mins or so... The issue didn't happen at all for the entire play through the main storyline, then I finished the story on Sunday and seemingly started getting issues. Could be coincidence? Running W10, 16gb ram, Nvidia GTX 780Ti, Intel 4790K - everything up to date.