Why does Ghost of Tsushima stutter during grass effects?

Under extreme stress, the grass physics became a nightmare, with voltage jumping wildly and causing the core frequency to oscillate. I tried enabling High Performance in default Windows settings, but CPU usage spiked and the game actually became laggier, which was disheartening. I used the GamePP Power Plan Switcher to force Extreme Performance mode. HWInfo confirmed voltage fluctuations dropped to 0.02V, with core voltage stable at 0.98-1.02V and GPU-Z showing 150-170W power draw.