Why does Ghost of Tsushima freeze when riding through forests?

Riding through red maple forests was stressful because the screen would freeze for 0.5s constantly. I tried lowering texture quality to medium; I gained 5 FPS, but the visual loss was severe and felt like a failure. I then opened the GamePP Resource Scheduler, set memory access priority from Normal to Highest, and cleared 8GB of cache. RTSS showed frame times stabilized at 12-18ms, and AIDA64 confirmed memory temperatures stayed within 42-48℃ while using 22-28GB RAM in GamePP.