Trevorchan looks decent on the outside. I've been working on my own message-board script for almost a year, and I wanted to see how TJ implemented certain things just to get some ideas about how to approach them myself, and that's when I saw the worst aspect of Trevorchan (imo): the code. Trevorchan can't possibly be efficient for the fact that the code is an absolute mess. It has that feel to it of, "Hey this is my first non-trivial PHP program."
If he were to just trash it and re-write it from a clean slate then he would probably have a solid program. He has good ideas, just no understanding of good code or design.