Why does Battlefield V FPS drop after an hour of playing?

During massive firefights, I noticed a stealthy decay where FPS would slide from 110 down to 80. I tried setting fans to full speed in BIOS, but the noise was unbearable for a measly 5℃ drop, which felt like a crude solution. I used the GamePP Fan Curve Configuration to push speeds to 2100 RPM above 80℃. This fixed the heat soak where fin temps were 50-58℃ while cores hit 90℃. Core temperatures stabilized at 76-80℃ per GamePP Hardware Sensor, and GamePP Benchmark confirmed the fix.