I have the same problem here now, I am 100% positive that this is a game issue, not a system issue.
I use "Gigabyte Thor 6000DPI 1055HZ polling rate (tested) even with a really good mouse like mine, and his, I still have the same problem. When ever I bring this up in community #OSU people just call me bad, as I did by a rank #227....
So I would like to request a developer maybe to look into this since I am 100% sure this is not system issue's
Frame limiter 120FPS any higher, game stutters because of FPS loss and gain.
Raw input not enabled, mouse acceleration not on, the pointer is in the middle of the slow ~ fast.
Also another weird thing I have noticed, possibly because of this buggy mouse, is that I'm over the note, press my key when I know I have to (you get what I mean) and somehow since my mouse is basically always moving (everyone's is, even tablet players are) and somehow amazingly, the note does not hit sometimes. This doesn't happen 24/7 but it does it enough to prevent you from keeping high note streaks. I can probably key this in with the buggy mouse, but IDK, some people say it's the latency or offset, but I'm pretty sure everything is set by the game, only thing I have changed is the FPS, raw input sensitivity (currently x1) and some map settings like softener filter and beatmap hits sounds and skins etc.