How to fix erratic FPS in Ghost of Yotei 4K scenes?

While traversing dense forests, I noticed my FPS jumping randomly between 50 and 70, which was incredibly obvious and distracting at 4K. I first tried updating the BIOS to optimize CPU voltage, but it only dropped the temp by 1℃ and the FPS jitter remained. I used the GamePP Fan Curve Configuration to lock the pump speed at a constant 90% and tuned the radiator fans. Frame times converged to 9-15ms per RTSS, and CPU temperatures stabilized at 72-78℃ per AIDA64 with fan speeds at 1100-1300RPM per GamePP.