Why does FPS drop when entering towns in Kingdom Come II?

Riding into a medieval town, the frame rate plummeted from 45 to 15 FPS, which was fatal for an immersive RPG. I first tried setting all graphics to the lowest, but the visuals became incredibly crude, leaving me feeling helpless. I entered the GamePP Resource Scheduler, raised memory access priority to Highest, and disabled the Windows indexing service. RivaTuner showed average FPS recovering from 22 to 38-44 FPS, and HWInfo confirmed memory temperatures remained stable at 40-46℃ during the ride.