We all want sites to load faster. For a developer, Apache’s ab only gets you so far, and frankly the server latency is only part of what defines the perceived speed of a site (and for Web 2.0+ sites that do a lot of work via Javascript, it may be a relatively small part). In order to measure the total time it takes a real-world browser to load a page, you have to test on the client side – upstream in the development cycle, where you can actually do something about the page architecture.
I found a great Firebug extension that does the equivalent of “ab”, but at the browser level. Using Hammerhead by Steve Souders, you can repeatedly hit a URL to measure the actual time it takes to load, and unlike “ab”, render it on your screen. It worked like a charm, enabling me to rapidly run A/B tests by changing variables on the server and client, to see the impact on performance.
Now if only Microsoft would make something similar for IE, the web could be a much better place.