Yet another quick&easy code timing function (and the getmicrotime() function from the earlier example):

$STARTTIME = getmicrotime();
$LASTTIME = $STARTTIME;
$TIMESTAMPCOUNT=0;

function PrintTimestamp()
{
__ global $STARTTIME, $LASTTIME, $TIMESTAMPCOUNT;
__ $now = getmicrotime();
__ echo "\n\n<!-- [TIME] ";
__ echo "Elapsed: ".number_format($now-$STARTTIME,4);
__ echo "_ Delta: ".number_format($now-$LASTTIME, 6);
__ echo "_ Now: ".$now;
__ echo "_ Instance: ".$TIMESTAMPCOUNT++;
__ echo " -->\n\n";
__ $LASTTIME = $now;
}

Call that function somewhere in your code, and it'll output this stuff:

<!-- [TIME] Elapsed:7.0750_ Delta: 1.747464_ Now: 1081451042.46_ Instance: 1 -->

Elapsed - Time since the code began (assuming those globals are at the top of your code)
Delta - Elapsed time since the last call to PrintTimestamp()
Now - System epoch time
Instance - increments by one with each call, useful for loop timing.