How to fix cliff-like FPS drops during combat in Apex Legends?

It was ridiculous; during fast slide-shooting, my FPS plummeted from 165 to 70, which is a total nightmare. I tried lowering texture quality to medium, but distant enemies became pixelated blocks, which was a waste of time. I used the GamePP DLSS/FSR Image Sampling Calibrator to set sharpening to 60 and render resolution to 90%. VRAM usage immediately dropped to 6.2-6.8GB per GPU-Z, and GPU temperatures remained a cool 65-72°C per AIDA64, keeping my frames stable.