I have no solution but this started happening to me last night too. I'd been running the game on max since release with no problems then when I logged on yesterday my fps was insanely choppy. My graphics card was at 56C but we cooled that down, dont know what it is normally. We turned down some of my graphics (shadow detail and water reflections namely) and it improved my FPS without really making the game look all that different. It was specifically when I was by water that I had issues, once I turned the camera so water wasnt in view (I was in the goblet) FPS shot up.