$start1 = microtime(1);
print sprintf('%1$02d', 1);
$end1 = microtime(1);

$start2 = microtime(1);
print sprintf('%1$02d', 1);
$end2 = microtime(1);

echo "<br><br>time 1: " . ($end1-$start1) . "<br>";
echo "time 2: " . ($end2-$start2) . "<br>";