I love how fast it is.

I used to hang out on a lot of phpBB and vBulletin forums, and one thing that puzzles me in retrospect is why their performance was so terrible. I can certainly understand how the first versions would be not so great, but the authors released many new versions over the years that tweaked the styling and added a few features but the performance was always awful. Seems like if the authors had put their minds to it those forums could have been super fast, which everyone would have loved because slow forums translated into bigger hosting costs...