Why does FPS drop during rat swarm scenes in A Plague Tale: Requiem?

The visuals are stunning, but rat swarms caused my CPU to hit 85℃, tanking my FPS from 80 to 40. I tried enabling High Performance mode in Windows; while the response was faster, the fan noise was unbearable and the drops persisted. I used GamePP Fan Curve Configuration to lock the pump speed at 100%. AIDA64 confirmed temps stabilized at 72-78℃, with water temps at 35-38℃, and RTSS showed the FPS finally stayed consistent. Absolute relief.