I do run Radarbox on a clean Windows XP installation. There are no other programs running like Virus Scanners, etc.
When I click on a menu button within Radarbox it takes a long time to open / close, etc. - approx. 15 - 25 seconds.
For example when I open the preferences and save it, it takes approx. 20 seconds to close.
I used Radarbox in full screen mode for over 24 hours. When I returned this morning to my PC and hit "ESC" for closing the full screen mode, the Radarbox closed the map, but did not reload any menus, etc. The complete screen went grey. So I had to terminate the application.
When I run other native OS programs on this PC like Wordpad, File Explorer, etc. everything works normal (e.g. menus opening within 1 second, etc.).