Why does Forza Horizon 5 stutter during high-speed driving?

While speeding at 300km/h on Mexican roads, I noticed frames suddenly plummeting from 110 to 65, creating micro-stutters that ruined the driving feel. I first tried setting the fans to full speed in the BIOS, but the noise was as piercing as an electric drill, making it completely unbearable. I used the GamePP Fan Curve Configuration Panel to steepen the speed slope between 75-85℃ and slashed the response delay from 2.2s to 0.6s. RTSS showed frame times converging to 8-13ms, and AIDA64 confirmed core temperatures stabilized at 74-79℃.