Why does NFS drop frames during nitro boosts?

Nitro boosts caused a painful drop to 60 FPS. Locking CPU frequency spiked heat. I used GamePP Power Plan Switcher for High Performance. Frame time stabilized to 6-8ms via GamePP, with CPU at 65-72°C per HWiNFO and 3.8-4.2GHz via Core Temp.