You've been asked to investigate why your web site is loading slowly. You've heard of WebPagetest.org so you enter the URL and run a test. What appears next is a colorful chart that looks like a Dr. Seuss illustration. Some bars are long, some are short. Some bars are blue, some are green. "That's nice," you say to yourself, wondering what to do next. It looks benign, innocently simple. But you know it holds many secrets.
The waterfall chart is a mysterious force to some developers. Performance gurus seem to be able to divine the ailments of a slow site at one quick glance. "How?" you wonder. The reality is that anyone can read a waterfall chart - if they know that they are looking for.
This presentation will bestow upon you the ability to recognize specific patterns in a waterfall chart, patterns which are the signs of a slow site. Using these newfound skills, you will become that performance guru and everyone will rejoice.
Presented to the San Francisco Web Performance Group on June 6, 2013.