UPDATE: Spoke with both osu support and nvidia support.
Basically osu support told me everything is fine with the game and the problem must come from somewhere else.
So I went and spoke with the nvidia support, tried a lot of things, nothing fixed it, they don't know what's causing it either and told me it should be a problem with the game.
- It could be a problem related to windows 10, but since it only seems to occur on laptops, i guess that's not the answer.
- Other thing i read about is nvidia optimus, the game could have some problems with it, i dunno, and the nvidia support said that if that's the case then the devs should be able to fix it.
I'm honestly tired of this, around 2 years performance problems on osu!, i love this game but i just can't play it anymore.
Devs please there are a lot of people with this problem, at least try to fix it, because it looks like you're not giving a shit.
also, with the newest nvidia driver update (399.07), it decreased even more my fps, i can't even get more than 200 now