make sure you manually stop storyboards on hidden objects

storyboards continue to run even if the object you’re animating is invisible, so you’re generally burning CPU cycles for nothing. in silverlight, you can stop any storyboard just by calling Stop:

myStoryboard.Begin();
myStoryboard.Stop();

in WPF, you need to specifically let the runtime know that you want Stop functionality when you call Begin via the isControllable paramater:

myStoryboard.Begin(this, true);
myStoryboard.Stop();