How to know why an animation stutters?

I have a few fairly simple animations (moving text around, moving ellipses etc.) and running in full screen (1920x1080 minus the task bar) the WPF Performance Suite reports a good framerate around 50 FPS throughout the animation. Dirty Rect Addition is somewhere around 300 rect/s, the SW frames are between 0 and 4 and the HW frames are between 3 and 5. Video memory usage is around 80 MB.

Problem is that the animations stutters every other half second. It is definitely not fluid :-(

My machine is a new Dell laptop XPS 15 with the GeForce GT 435 with 2GB memory. - The drivers are up to date. (The same behavior occurs on my netbook (in full screen) as well so I don't think it is hardware related.)

If I make the window smaller the stutter goes away.

The stutter occurs with the simplest of animations - even with just a couple of elements but adding more elements certainly makes it more noticeable.

How can I find out what causes this stutter?

When I think of it, I have not actually seen any WPF animations which run smoothly in full screen. Is this even possible?