Same problem - Kaspersky taking up constant 20 - 30% CPU. Working through the Microsoft Support article referenced by Anton Mefodys did the trick, though it took me well over an hour. In my case (on a Dell Inspiron 5000 series running Windows 10) the culprit turned out to be “True Color” which was enabled to run at Startup. If you’ve got the same issue, check if you’ve got that running and try disabling it (Task Manager » Startup » right click on True Color, Disable » Restart); if that works, you’ve saved yourself some time, otherwise, it’s back to Anton’s MS article and work through it. Since I also am using a Dell Inspiron I decided to try disabling True Color, and it fixed my high CPU problem too. Thanks for suggesting this!