Mathias Bynens 13 December 2011 Nice write-up, Scott! Just a few clarifications: * `document.querySelectorAll(’:hidden’)` doesn’t actually work; in other words, supporting QSA doesn’t affect the performance of jQuery/Sizzle’s custom selectors. (The text makes it seem like it does.) * The reason Opera scores so well in QS/QSA tests is because it caches the results. It would be tricky but interesting to create a performance test case that works around this by avoiding repeated selectors.