When you open a new window from within a tab the open animation sort of animates in a jagged/shocking way. As if the animation is rendered using large blocks with a height of ~100pixels at a time. Even the root window's background color often shows in the bottom half of the screen.
I managed to capture the effect in a screenshot using the iPad Retina simulator.
You can reproduce the issue by creating the default Classic/Tabbed application template and opening the window. The effect is most obvious on a retina iPad in landscape.
This is the call that triggers the open with the default animation.
The issue has been in Ti SDK for as long as I know. I always thought I was doing something wrong, but I am not... So time to report the issue cause apparently no one else is seeing it...