I have seen this a few times and i have seen the cheaters reverse at the start, but the thing that annoys me is the lag you get when your actualy racing. I know its not my computer so i can only suspect that its the server or my internet connection. I have only had lag when racing 2 or 3 times and i have races 200 to 250 races now with 86 race wins, as annoying the lag is, its inevitable that the game will lag for what ever reason at some point.
My tip is to make sure your computer is maintained ie. Disc clean up, defrag etc etc, this will reduce the chances of lag but it will not stop it, also make sure your settings are not the reason for lag. But from the sounds of it, your not experiencing lag yourself so your settings must be fine. Apart from them alway's think ahead and be ready for a slow starting driver.