There’s an interesting assumption that because the Labs group is working on new ways of lightweight customization for the subset of the Firefox audience who’s interested, the platform and product development teams aren’t working on speed, performance and correctness issues with the core product. That’s obviously not the case, as evidenced by the Firefox 3.5 nighties that are produced every day, and which all perform a little bit better, are a little bit more secure, and a little bit faster.

The “browser wars” (which aren’t wars, really, but innovation and software development methodology races) won’t be won by a single issue like lightweight customization of the theme, no, but they will be won by organizations who can iterate on several fronts at once.