This is a speed test of your browsers javascript engine, yes, javascript can be a primary factor of speed. Once the html and script have been downloaded by your browser, it must get parsed and processed by your browser. I honestly wasn't surprised as to which browser outperformed the rest, it's code is written so low level.
Javascript Browser Speedtest
Page rendered at Saturday, July 31, 2010 6:18:45 AM (Eastern Standard Time, UTC-05:00)