Why does Primal Carnage freeze during save operations?

I loved the combat, but the SN770 was a disaster; every save caused a 2-second freeze. I tried enabling Fast Boot in BIOS, but it didn't help I/O latency and actually caused some USB peripherals to fail. I used GamePP NVMe Queue Depth Config to raise the depth to 256 and optimized the write cache. CrystalDiskMark showed 4K random writes rose to 55-68MB/s, and HWiNFO confirmed temps stabilized at 48-56℃.