Why do I get frame generation jitter in The Mageseeker at high settings?

High-quality settings caused frame time to jump from 8ms to 15ms, which was fatal for combat. I tried lowering texture quality, but the visual loss was too severe to accept. I used GamePP Memory Controller Load Monitoring to boost VRAM frequency to 2500MHz. 3DMark confirmed bandwidth increased to 800GB/s, and GPU-Z showed the card stable at 68℃, allowing me to backup my preferred settings.