Why does Hitman 3 drop to 45 FPS on Vastarmor RX 7800 XT?

I was stuck in a stealth mission when the frame rate plummeted from 60 to 45 FPS, totally breaking my focus. I tried manually overclocking the VRAM to 2200MHz via GPU-Z, but it caused severe visual artifacts and made things worse. Using GamePP Hardware Sensor, I found VRAM usage spiking above 95%. I used DDU to clean install the latest Adrenalin driver and adjusted the scheduler. Now, AIDA64 shows VRAM temp stable at 65-70℃, and Fraps confirms 58-62 FPS. The config is saved.