Unfortunately for the moment there is no way to optimize the page flip. However, we've made research on the topic and we believe that there is a way to optimize the animation by converting the pages to a WritableBitmap during a page flip. There is an item in out public issue tracking system which is called "Book: Convert pages to WriableBitmap during page flip"
and is associated with this particular functionality. We will do our best to implement this feature for our Q3 official release, but I cannot bind to that with 100 % certainty. That's is why I'd suggest you track and vote for the PITS item because items with higher votes get higher priority.
All the best,
the Telerik team
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