PHP as a module in Apache!(Apache1.3.24 + PHP4.2.1)
<?php
// A function that records the time when it is called
function profile($dump = FALSE)
{
    static $profile;

    // Return the times stored in profile, then erase it
    if ($dump) {
        $temp = $profile;
        unset ($profile);
        return ($temp);
    }

    $profile[] = microtime();
}

// Set up a tick handler
register_tick_function("profile");//here have a bug,but on win32+PHP4.2.1 no problem!

// Initialize the function before the declare block
profile();

// Run a block of code, throw a tick every 2nd statement
declare(ticks=2) {
    for ($x = 1; $x < 50; ++$x) {
        echo similar_text (md5($x), md5($x*$x)), "&lt;br&gt;";
    }
}

// Display the data stored in the profiler
print_r(profile (TRUE));
?>