test.php

<?php

class Foo
{
  public function __construct()
  {
    sleep( 1 );
  }
}


/**
 * With new
 */
$collec = array();
$first_start = time();

for ( $i = 0; $i < 10; $i++ )
{
  $collec[] = new Foo();
}

$first_stop = time();
echo $first_stop - $first_start . "\n";


/**
 * With clone
 */
$collec = array();
$second_start = time();
$carbon = new Foo();

for ( $i = 0; $i < 10; $i++ )
{
  $collec[] = clone $carbon;
}

$second_stop = time();
echo $second_stop - $second_start . "\n";