In a WPF 4 app, I have a very big user control full of controls which takes something like 4s to initialize on a fast machine. During this time the application is of course not responsive at all.  

Is there a way to show an animation in the main window while this control is initialized? 

I understand that I cannot create it on another thread. But is there maybe a way to create it with a lower priority from the Dispatcher so that I could show a spinning wheel or so on the main window which would still spin?

(The only solution I can think of right now would be to break the user control into further pieces and load them only when needed. But this will take a lot of development time to change.)

**Update1**  

To be more clear: It is a simple WPF window using tab pages. When a new tab page is opened I'm initializing the user control which holds the controls for this tab page. One of these user controls is so full of controls that it takes 4s until the new tab page will be shown.  

So I thought showing a spinning wheel would be better than having a blocked application.