Facebook made quite a splash when they released their native iOS app, not because of their app per se, but because of their conclusion that their biggest mistake was betting on HTML5, so they had to go native.
As you might imagine this was a bit like telling a Great White Shark that its bark is worse than its bite. A common refrain was Facebook simply had made a bad HTML5 site, not that HTML5 itself is bad, as plenty of other vendors have made slick well performing mobile sites.
An interesting and relevant conversation given the rising butt kickery of mobile. But we were lacking details. Now we aren't. If you were wondering just why Facebook ditched HTML5, Tobie Langel in Perf Feedback - What's slowing down Mobile Facebook, lists out the reasons:
- Tooling / Developer APIs. Most importantly, the lack of tooling to track down memory problems.
- Scrolling performance. Scrolling must be fast and smooth and full featured. It's not.
- GPU. A clunky API and black box approach make it an unreliable accelerator.
- Other. Would like better touch tracking support, smoother animations, and better caching.