Thanks for the hints,
tried the V-Sync option in nVidia control panel,
set spice64.exe vsync to on.
From the observation it got some improvement,
however it cannot solve the problem completely.
I tried a bunch of more songs,
apparently, it's not because of the chart running slower than BGM,
it's due to frame-dropping / stuttering.
after V-sync is on, I can clearly see the visible stuttering from time to time,
and after the stuttering then the chart is lagging behind the BGM.
I tried again with the same spicetool config with iidx 29 (2022050900),
work perfectly fine.
This behavior is totally in sync to the report of many Taiwan IIDX arcade players reports raging about frame dropping / stuttering specificly on iidx 30.
I think now have to wait for future updates then.
Testing on 3080 / 5950x / 64GB, I don't think it's due to under power
will try will some AMD display card later