I'm experiencing the same issue with RadTransitionControl for Silverlight 5. Have you found any solution for this? Do you have an answer from Telerik?
EDIT: John and Telerik team, making some tests, I was able to reduce drastically the
memory consumption by manually calling GC.Collect() after assigning the
Content to the RadTransitionControl.... although this is not a good
practice... what does Telerik team can suggest about this?
radTransitionControl.Content = control;