[mikeash]

Scrolling has a noticeable and jarring pause when reaching the top or bottom of the list, and in general isn't smooth when the "pull to refresh" area is visible, at least on my 4S. It's really good overall, but definitely not quite in the realm of no noticeable difference from a native app.

[chrisringrose]

This is a result of Google's decision to not "perfect" this on their web app - but it could be. It's just low priority.

Just as there is lag and jittery scrolling when loading older posts in the Android native Facebook app, it's not a result of the platform, but a result of poor design, or not putting the effort into that one area of optimization.