I should have clarified. Combo of Starling/DisplayList is used on the app versions (iOS and Android).
The web version uses Standard DisplayList only (to maximize audience reach).
App performance is actually smoother than the web version.
The project was conceived as an app first, then ported over to desktop, so app performance was critical. HTML5 and CSS3 app performance couldn't smoothly handle the giant bitmaps and long animation sequences.