I'm using Google Chrome 91.0.4472.77 on Windows 10. Notes run smoothly, but seem offbeat a little.
I do not exclude that this is just me, but if I'm the only one who think they are offbeat means that the problem was between my chair and my keyboard :D
Ah cool - probably personal preference then? I did the beat mapping with osu, so it definitely lines up with the song tempo wise. I'm not super-familiar with rhythm game idioms, so it's possible there is some "game feel" voodoo you've grown accustomed to which I haven't implemented.
Right now if you hit the beat slightly off center the drum sound will also play off beat, and the window for hitting a beat is pretty permissive (like a quarter of a second). So if you are consistently getting "Goods" instead of "Perfects" there will be a disconnect between your input and the song, even though the game is grading you well.
Anyway, thanks a lot for the extra info! If more people have issues with the rhythm game I'll look into the problem some more.