What can cause stutters in game after some time of playing?

The races start ok. Just after a couple of minutes the game stutters, always at same places (curves)

I would relate that with high temperatures, but they are ok - GPU and CPU

I have a GTX 770, by the way. Windows 8.1

Original Writen by E_Luckow in PC - Technical Help & Support Category, the date of 24-06-2015 04:06.