Developers should take heed of the "uncanny valley" point Andrew makes. While I come across the rare example of an app that pulls off stock UI via CSS well [1], most fail somewhere along their approach and end up subtly repelling the user.
I wrote a PhoneGap app [2] and this fact was among my considerations when designing it.
The performance points are spot on with my experiences, especially avoiding any height and width manipulations. Most of the height transitions in my app are actually translations on the Y axis, preventing reflows. Rather than completely rely on the browser's native layout capabilities, it can pay off tremendously to do some of those calculations and translations manually.
I wrote a PhoneGap app [2] and this fact was among my considerations when designing it.
The performance points are spot on with my experiences, especially avoiding any height and width manipulations. Most of the height transitions in my app are actually translations on the Y axis, preventing reflows. Rather than completely rely on the browser's native layout capabilities, it can pay off tremendously to do some of those calculations and translations manually.
[1] - http://cheeaun.github.com/hackerweb
[2] - http://chaincalapp.com