<?php
$t = microtime(true);
for($i=0;$i<100;$i++) {
echo '.';
}
$t1 = microtime(true)-$t;
$t = microtime(true);
for($i=0;$i<100;$i++): ?>.<?php endfor;
$t2 = microtime(true)-$t;
echo PHP_EOL;
echo 'Within PHP: ', $t1, PHP_EOL;
echo 'Outside PHP: ', $t2, PHP_EOL;
echo 'The fastest is ', $t1 > $t2 ? 'Outside PHP' : 'Within PHP';