While our initial review of Internet Explorer 7 and Firefox 2 focused on cataloging their new features, this follow-up test put the new browsers through an extensive range of trials. These tests, of development standards conformance and page performance, were designed to show that browser choice can  affect greatly how well users access Web content.

We found that in standards conformance, Firefox 2 is the measurably dominant browser. Performance results varied widely depending on the test case and Web site used (see "Tracking browser Performance," below). We did see somewhat of a trend that Internet Explorer was faster than Firefox, though we also found that older, less-compliant browsers (that is, IE 6 and Firefox 1.5) were faster than their upgraded brethren. Interestingly, our control browser, Opera 9, struck a nice balance between performance and standards conformance, and warrants a deeper look from those who want it all

In our testing of markup conformance, we found that no browser supports perfectly even older markup specifications, such as HTML 4. If you poke around the HTML and XHTML specifications hard enough, you will find many little and occasionally some big problems in the browsers.

The markup omissions were more notable with IE. For example, IE 7 does not support a number of character entities, including useful math symbols. It does not support the <q> tag, nor does it support all aspects of how the <object> tag should act, such as pulling in external files. Firefox 2 also had some problems with <object> and a few issues with test cases for the <textarea> tag.

Click to see: Tracking browser performance