How to fix CPU frequency fluctuations in Defense Grid sandstorms?

Facing blinding sandstorms, my CPU load would spike, causing an unpleasant stutter that severely killed the immersion. I tried enabling Power Saving mode in BIOS; while temps dropped 5℃, FPS plummeted from 60 to 42 per RTSS, which was a terrible trade-off. I used the GamePP Fan Curve Configuration to set 75℃ as the full-power threshold and applied a -0.03V offset. AIDA64 stress tests showed temperatures stabilized at 76-82℃ and the clock speed finally stopped jumping around.