Why does Metro Awakening stutter on the ASRock H310CM-HDV board?

I was mid-defense in Metro Awakening when character movement lagged badly. I tried increasing the page file size, but it dropped FPS from 78 to 61. I used GamePP BIOS Wizard to lower timings from 16-18-18-36 to 14-16-16-34 and raised voltage from 1.20V to 1.25V. AIDA64 showed latency dropped from 102-115ns to 76-82ns. MemTest86 confirmed zero errors, saving the stable memory parameters.