What Release Stream are you on? Are you sure it is osu! that is using up resources and not some other program running in the background? You can use something like Process Hacker to see which programs are using your CPU at specific times.
Make sure all of your drivers are up to date. Check to make sure your CPU/Computer is not overheating. And this may seem simple, but have you restarted your computer?
Make sure all of your drivers are up to date. Check to make sure your CPU/Computer is not overheating. And this may seem simple, but have you restarted your computer?