Why does PUBG FPS drop from 140 to 60 in complex urban areas?

Entering Pochinki caused my frames to crash from 140 to 60, making my movements feel incredibly sluggish. I tried updating to the latest drivers, but the frame drops persisted, leaving me feeling helpless. I used the GamePP Resource Scheduler to set process priority to Realtime and enabled VRAM bandwidth priority. Frame intervals converged to 6-11ms per FrameView, while memory controller load stayed under 95% per AIDA64 and temps hit 68-75°C per AIDA64.