Why does MGS Delta drop to 40 FPS during firefights?

During tactical pushes, the frame rate randomly drops to 40, making me overly cautious in competitive matches. I ran the Windows Memory Diagnostic tool, but it showed everything was normal while the drops persisted. I used the GamePP Fan Curve Configuration Panel to lower the fan start threshold to 55℃ and max speed to 1800 RPM. CPU temperatures stabilized at 68-75℃ per AIDA64, and Vcore voltage remained steady at 1.2-1.3V per HWMonitor, eliminating the 1.1V dips.