Why is Neverness to Everness loading so slow?

I noticed loading times in Neverness to Everness increased during island exploration. Increasing virtual memory failed and dropped frames to 30 FPS. I used GamePP to set 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 7000MB/s.