I recently discovered apd and I ran it up against our site's framework.  Imagine my surprise when I saw that I was hitting strlen 27917 times! It turns out that I heavily use PEAR DB's prepare() functionality.  In the current CVS, the prepare function is:

    function prepare($query)
    {
        $tokens = split("[\&\?\!]", $query);
        $token = 0;
        $types = array();

        for ($i = 0; $i < strlen($query); $i++) {

But if I change it to:

        $length = strlen($query);
        for ($i = 0; $i < $length; $i++) {

I was able to shave almost 2 seconds off of my uncached render times.   

Don't think for a minute that I don't love PEAR::DB.  I appreciate all your hard work and recommend it constantly.

Thanks!
- Dan