I'm unconvinced. Web pages scroll fine for me, why can't the timeline and newsfeed?

Scrolling and js performance differ radically between web pages in mobile safari and uiwebviews on iOS.

Because it's infinite scrolling. They add stuff while you scroll. That's much more difficult to make smooth.

Here's an insightful and rather good approach (at least to me when I tried to implement something along the lines of this): http://engineering.linkedin.com/linkedin-ipad-5-techniques-s...

Why can't they just load when you reach the end? I've found this tends to be what happens for me, anyway.

They could do that, but they don't want to. Their point is that web technologies can't deliver the experience they want. Telling them they want dumb things is not a legitimate response, especially as they can get the experience they want using other technology.

Seems like an issue they've struggled to solve unsuccessfully, and it's a pretty big problem for a core feature of their product unless they change the UI altogether for how they present the feed. Is there an example of an infinite scroll UI that pre-fetches text / image content on mobile web without the uncanny valley problem?