Really sorry for the inconvenience, vladvanek. We'll be sure to help you out with this.
This kind of performance issue, scan hangs issue, is usually caused by other security programs or potentially unwanted programs that might be installed on your PC. Kindly check on your Installed Programs list and uninstall any other security programs or potentially unwanted programs on the PC. You may also try to run the permission tool.
Hope this helps. Please let us know if you need further assistance. Thank you! :)