Web Tech - refactoring and improving performance

I'm following Joel Spolsky's advice in "Fire and Motion" and trying to work on that thing every day, as much as I can, no matter that my work is not "perfect". If I manage to steal an hour of "zone" time a day I'm happy with my progress - it gets better, faster, cleaner as I go along. I'm using an oldschool version control system (solid RAR archive of timestamped directories, one for each version, each self-contained) and document ideas in a "to-do" section. Most of the code has been re-written twice already, and each time I'm astonished how bad it was. That should mean it's iteratively getting better. I've learned to appreciate ECMAScript functions as first class objects, closures, and most recently the fact that array.reverse() is "free" performance-wise. Also I noted that IE's DOM has been optimized only for sequential access, while Mozilla also does decent random access. In general, Mozilla is so far ahead of IE (despite its cross-platform compatibility) it's staggering. The usefulness of the DOM Inspector tool is beyond words.