Why does my FPS drop in Saint Denis with 4K MODs enabled?

I was devastated when riding through Saint Denis; 4K mods pushed my CPU to 82-86℃ per AIDA64, and my FPS tanked from 60 to 35. It totally killed the immersion. I tried setting the fans to full speed in BIOS, but the noise hit 45dB while temps only dropped by 2℃—a total failure. I finally used the GamePP Fan Curve Configuration Panel to set a steep 1800-2300 RPM curve for the 75-90℃ range. During 3DMark tests, peak temps stayed at 82-86℃ per HWMonitor, and frequency fluctuation narrowed to 0.1GHz per CPU-Z.