Apple has released Speedometer 2.0, a benchmark that lets you test your browser’s web app responsiveness. The tool is part of Apple’s contribution to WebKit, a collaboration between Apple, Adobe Systems, Google, KDE, and others.
Speedometer 2.0 works by simulating “user interactions.” Essentially, it runs 480 tasks and then measures how long it takes your browser’s speed in carrying these out, before providing you with a report.