Why does FFVII Rebirth drop frames during camera rotation?

Walking through Midgar was stressful; any quick camera turn caused my FPS to plummet from 60 to 35, which gave me huge anxiety. I tried lowering all shadow quality to Low, but the visuals became hideous and the stuttering continued, leaving me defeated. I then used the GamePP DLSS/FSR Image Sampling Calibrator to drop the rendering scale to 85% and enabled DLSS Quality. Frame times finally converged to 14-18ms per RTSS, and VRAM temperatures remained stable at 58-63℃ per HWInfo and 65-72℃ per MSI Afterburner.