i think one idea behind animated page transition is to increase performance experienced by the user.

This will work when silde animation starts immediately after the user clicked on smth. and just showing a progress bar when the content is still not ready after the animation finished.

In my opinion JQM does transition animation in wrong order. First, jqm starts the progress bar and if content is ready jqm start the animation. In fact this will extend waiting time. Reordering animation will increase user experience