Why do I get micro-stutters during Nioh 2 combat?

I felt totally defeated when fatal micro-stutters ruined my parries during high-difficulty Yokai battles. I tried enabling Full Speed mode in the BIOS, but the fan noise sounded like a helicopter while AIDA64 showed temperatures only dropped by 2℃. It was useless. I then used the GamePP Fan Curve Configuration Panel to steepen the slope for the 70-80℃ range, pushing speeds to 1800 RPM. RTSS confirmed frame times dropped from 14-22ms to 11-13ms, and AIDA64 verified CPU temps stabilized at 68-74℃.