Why do I get random micro-stutters in Neverness to Everness?

While exploring the open world, the screen freezes momentarily every few minutes, which is very mood-killing. I first tried increasing virtual memory to 64GB, but this didn't solve the stuttering and instead increased disk I/O pressure per HWInfo64, leaving me helpless. I used the GamePP Memory Calibration Tool to adjust primary timings to 16-16-16-36 and increased memory voltage to 1.35V. MemTest86 showed errors dropped from 3 per hour to 0 and memory temps remained at 40-46℃ per AIDA64 to verify.