Why does my frame rate drop during RDR2 4K MOD combat?

During a Saint Denis firefight, my FPS plummeted from 120 to 85 as the Kioxia EXCERIA G2's SLC cache overflowed. I tried cleaning temporary files, but that did nothing to stabilize the frame rate, leaving me exhausted. I used GamePP Resource Scheduler to limit background write priority and enable forced cache refresh. RTSS monitoring showed frame time intervals converged from 10-15ms to 8-10ms, and AIDA64 confirmed drive temperature stable at 48-52℃. The combat flow is finally smooth and predictable.