Why does my CPU throttle during Horizon Zero Dawn battles?

I felt totally cheated when fighting Thunderjaws; the screen stuttered so hard it killed the immersion. I tried setting all fans to full speed in the BIOS, but the noise was deafening and core temps still hit 96℃ per AIDA64, which was just frustrating. I then used the GamePP Fan Curve Configuration Panel to ramp fan speed to 90% at 75℃ and shortened the sampling interval. Finally, core temperatures stabilized at 78-84℃ per RTSS, and frame times dropped from 12-35ms to 8-14ms per FrameView. I feel so relieved now.