Why does FF16 stutter during combat summons?

Stuttering during summons was maddening. I tried virtual memory tweaks, which made it worse. I used GamePP NVMe Queue Depth to raise it to 2048. CrystalDiskMark showed 4K random read jumping from 45-52MB/s to 68-75MB/s, and load times cut from 12s to 5s.