Unity Editor freezes / not responsive

I have this problem since last week. When I click on an UI element in the editor it takes a while until it becomes responsive. When I change to another window like the inspector I will have to click it a couple of times and wait until anything is clickable.

I have tried these things already:

-Reinstall Unity (incl. new version)

-Reinstall Graphics Drivers

-Test new project incl. one on another harddrive

-Uninstall other programs that might cause the issue

What has helped is reinstalling windows. But now after a couple of days the same problems occurs again.

I have no idea what the problem is. Any ideas? Thanks!