Is this a new problem? IOW, was it previously working for you?
Does it happen in the Named or UnNamed People tabs or both?
Are you getting any error messages?
If on Windows, does Task Manager show any Organizer activity?
How large is your catalog?
With the little information you have provided, I can only speculate that media analysis is taking place in the background. To determine if this is the cause, go to Edit>Preferences>Media Analysis and uncheck all the boxes. Restart your computer and see if the problem still exists.