How to fix frame time fluctuations in Starfield city centers on DDR5?

I was thrilled to land in a new planet's city center, but the immediate stuttering quickly killed the excitement. I first tried lowering texture quality, but the game looked like it was from ten years ago and FPS only increased by 5, which felt like a waste of hardware. I used the GamePP Resource Scheduler to set the game's memory page priority to highest and optimized the CPU cache prefetch strategy. RTSS monitoring showed frame times converging to 14-18ms, with memory temperatures stable at 52-58℃ per HWiNFO and usage at 14.2-15.8 GB per AIDA64.