I've sometimes thought that optimizing web applications is as much a science as dowsing. (No offense intended, dowsers of the world — but you have to admit it's a hard thing to explain even when it does work out.) Even when you are completely willing to invest time and energy into optimizing an application, how do you actually go about it?
We couldn't take it anymore. We decided we had to find a way to transform the witchcraft of optimizing web apps into a legitimate engineering task, once and for all.
Happily, we've managed to land these changes into both WebKit and Chrome over the last several weeks. Soon you'll see the first examples of tools that make these metrics available to web developers using WebKit-based browsers. Of course, we have a lot more instrumentation planned, but the ball is really rolling now thanks to lots of help from the friendly folks on the WebKit and Chrome teams (especially Pavel Feldman and Timothy Hatcher). We've gained many new insights, some of which I mentioned in my Measure in Milliseconds talk at Google I/O earlier this year. When you see these metrics yourself for your own web apps, you'll likely be surprised — and you'll almost certainly wonder how anyone tried to write high-performance code without this sort of insight. Be sure to keep an eye on the Chrome Dev Channel and the WebKit nightly builds for new Inspector features based on our work.