one-loop.php

<?php 


$cnt = 10000;
$st = microtime(true);
foreach( range(0,$cnt) as $idx ){

  $list = range(0,1000);
  foreach ( $list as $i=> $e  ) {
    $e = strtotime("+$e day");
    $e = date("Y-m-d", $e);
    if( preg_match('/-03-/', $e) ) {
      $list[$i] = $e;
    }else {
      unset(  $list[$i] ); 
    }
  }
}

$time = microtime(true) - $st; 
echo "one-loop : $time \n";