[webkit-dev] optimizing browser handling of Facebook Timeline scrolling

[Geoffrey Garen]

> If anyone needs a test page, you can log in as my test user
> styoung.travel at gmail.com (pwd:browsertest). Then go to
> https://www.facebook.com/styoung.

Nice!

I took a trace of this timeline and saw similar results as before (lots of time computing .offsetHeight and .scrollLeft), but with less time spent in image drawing. (Perhaps I have higher resolution photos in my timeline.)

> Btw, what tool are you using that tells you what item is being
> repainted when the cpu is pegged?


Mac OS X ships with a performance analysis tool called "Instruments".

Documentation overview:

https://developer.apple.com/library/wwdc/ios/#documentation/DeveloperTools/Conceptual/InstrumentsUserGuide/Introduction/Introduction.html#//apple_ref/doc/uid/TP40004652

Recent WWDC presentation:

https://developer.apple.com/wwdc/schedule/details.php?id=310

Instruments analysis doesn't work very well with the current shipping version of WebKit, but it works great with WebKit nightly builds (nightly.webkit.org).

Geoff