Why does Nioh 2 drop frames during intense combat with particle effects?

During high-intensity action duels, the frame rate would suddenly plummet from 60 to 40, which is absolutely fatal when trying to parry. I first tried enabling Extreme Performance mode in the BIOS, but it caused random freezes on the loading screen, leaving me feeling helpless. I then used the GamePP Memory Controller Load Monitor to tune the XMP profile down to 5800MHz and lowered the voltage to 1.32V. AIDA64 stress tests showed latency stabilized at 63-69ns, and GamePP confirmed temps at 48-54℃.