Why does Tomb Raider stutter in exploration scenes?

Exploration scenes in Tomb Raider flickered like a broken projector. Increasing virtual memory failed and dropped frames to 30 FPS. I used GamePP to increase NVMe queue depth from 1024 to 2048 and enabled forced write cache refresh. CrystalDiskMark confirmed 4K random read speed improved from 45MB/s to 68MB/s, and sequential read speed reached 3500MB/s.