Almost every time I play after a certain time the game runs at half speed and even the frame rate became the half then after about a minute suddenly accelerate (it seems a time warp) and return to run at normal speed. It always happens when I return to game after I saw a replay. Does it happens to you?
If I understand what you mean, you are having a strong fps drop during a minute that is causing the game to run on "half speed". Is it happening in all tracks or just one? Have you tried reducing the graphics quality (reflections, shadows, anti-aliasing) to see if the problem persists? Maybe a new process running on Windows background that is consuming some of your PC resources while you are playing (this happened to me once in another game)?
That could be CPU throttling. I remember a similar thing in PC2. Also, check your power settings in windows for CPU min/max% and set them to 100%.
Make sure your CPU doesn't overheat. If you are overclocking the CPU, remove the OC and see if the slowdown happens again. Your system specs would help with troubleshooting, btw.
