hello, sorry for bumping into an old question lol
I have a trick to solve this. idk if this trick works for you guys
if you have your osu is running, close it first. then go to the file and open your osu! folder (C:\Users\Username\AppData\Local\osu! or anywhere you put it), and find
osu!.<your pc username>.cfghttps://osu.ppy.sh/wiki/en/Client/Program_files/User_configuration_fileright-click, open with notepad, scroll down and find Width and Height.
now here's the trick, if you have like 1920x1080 monitor, write that in the cfg or the notepad and decrease it by 1.
for example Width = 1920 Height = 1079. or if you have a 1280x720 monitor, then write Width = 1280 Height = 719. then save it if you're done. then open osu. go to options and turn on render at native resolution. it works for me
I have this old hp laptop with intel HD graphics. when windowed, it's over 120fps but when fullscreen mode is always under 50, and the screen was also teared and this work perfectly fine