Como verificar o tempo de carregamento da página no PHP

$startTime = array_sum(explode(" ",microtime()));
error_log("Started time=======".$startTime);


echo "=======Your Code=======";
echo "=======Your Code=======";
echo "=======Your Code=======";
echo "=======Your Code=======";
echo "=======Your Code=======";


$endTime = array_sum(explode(" ",microtime()));
error_log("Started time=======".$endTime);

$timeTaken = round(($endTime - $startTime),2);

error_log("Page loaded in $timeTaken seconds");
@CodeGrepperManu