Why do I experience 0.4s stutters in God of War Ragnarök?

I was so excited to finally fix this! Facing giant bosses, the screen would stutter for 0.4s due to Vcore voltage jumping between 1.10-1.25V. I first tried disabling all power-saving options in Windows, but it only gained 3 FPS and raised temps by 4℃, which was discouraging. I used the GamePP BIOS Load-Line Voltage Adjustment Wizard to switch LL mode to L3 and manually added 0.02V offset. RTSS showed frame times converged to 12-16ms; HWMonitor confirmed GPU temperature stable at 66-72℃.