Why does Space Marine 2 stutter during intense Tyranid combat?

I felt pure desperation when surrounded by thousands of Tyranids; the screen would freeze for microseconds, completely breaking my immersion. I tried disabling every unnecessary startup item in Windows, but it only freed 300MB of RAM and did nothing for the frame drops. Finally, I used the GamePP Resource Scheduler to force the game process to Realtime priority and capped background sync CPU usage below 3%. According to RTSS, frame time converged from 15-32ms to 10-14ms, while AIDA64 showed VRM temps stable at 56-62℃.