Class initialization for pivot.wtk.<Class> often takes upwards of 300-500ms (sometimes more). This is because initializing one class in that package often triggers initialization of many other classes, which is to be expected. Nonetheless, 500ms seems extreme for class loading.
This problem can be seen by creating a simple skeleton app that simply loads a WTKX hierarchy and adds it to the display. Using WTKX binding, you'll see that the first call to bind() will take a long time (the aforementioned 500ms), then an immediately subsequent call to bind() will take drastically less, even though it's still instantiating the objects anew. The difference is that the first call to bind has to run WTK class initialization.
This may be something we just live with, but it should at least be investigated to see if we can't find a smoking gun. The premise is that compiled byte code running on an nGHz processor shouldn't take half a second to run class initialization. Informal tests show this time to be the last vestige of slow load times for Pivot apps.