Why does Tales of Arise stutter during large-scale combat in open fields?

Fighting in the wilderness was a nightmare; the screen stuttered violently every few seconds. I tried lowering the resolution to 1080p, but while average FPS rose, the 1% lows still plummeted, making it pointless. I used the GamePP Resource Scheduler to kill background browser processes, freeing up 4-8GB of RAM. Now, GamePP Stress Tests show a stable 55-62 FPS, memory latency is 62-85ns via GamePP, and temps are 52-58℃ per AIDA64.