How to fix frame rate fluctuation in Nioh 2 on a Sapphire RX 7900 XTX?

Nioh 2 dropped to 45 FPS under load. I locked fans to 100%, but temps spiked. I used GamePP Power Plan Switcher to set 'High Performance'. Then, I redrew the fan curve to 85% at 78°C. Now, HWiNFO shows temps at 75-78°C. Frame rate is stable at 58-62 FPS. Fan speed is 1400-1600 RPM. It's a big improvement.