Why does Helldivers 2 stutter on ASUS X870-A and how do I fix it?

Map switching in Helldivers 2 was a nightmare; my ASUS ROG STRIX X870-A dropped to Gen3 x4, cutting read speeds to 2500MB/s. I re-plugged the drive, but it just caused system instability. Using GamePP’s BIOS Wizard, I forced Gen4 x4 and tweaked the voltage offset from +0.02V to +0.01V. CrystalDiskMark now shows 6800-7200MB/s, and load times dropped from 15s to 5s. Drive temps are stable at 45-52°C per AIDA64.