Two tracks have a bug or optimization is needed and I'm not sure what the official channel is to report this so I'm posting it here hoping you will see it. I've noticed on the Portimao National Circuit when you get past the first 2-3 turns and crest the hill that the framerate drops and the game stutters for about 15 seconds or so as you keep going through a few more turns before it goes back to normal. Lowering track detail to medium seems to fix this issue as a temporary workaround. I've also noticed on the Monza Junior Circuit when you go into the first 3-4 turns, the same thing happens as Portimao, except it doesn't last as long, maybe 7-8 seconds. Lowering track detail to medium has no affect on this issue. These are the only two tracks that I have seen this issue. My PC specs: Intel i5 2500k @4.4GHz Two GTX 780's in SLI here, but SLI doesn't work on this title. 16GB of 2133MHz memory.