Why does Phantom Blade Zero drop from 90 to 40 FPS?

During fast-paced combat, my frame rate plummeted from 90 to 40, which totally ruined my combos. I first tried lowering the in-game resolution, which added 10 FPS, but the stutters from CPU throttling remained. I used the GamePP Fan Curve Configuration to trigger max fan speed at 70℃ and tuned the CPU offset voltage to -0.03V via HWInfo. RTSS monitoring showed frame times converging from 20-45ms to 12-18ms, and GamePP confirmed CPU temperatures stabilized at 82-88℃.