Description:
------------
If I set object property run-time it uses more memory than equal default property value.

Test script:
---------------
printf("PHP %s %s\n\n", PHP_VERSION, PHP_OS);

class Order {
	public $id     = '123';
	public $number = '1234';
	public $date   = '12345';
}

$orders = [];

printf("Test1\nMem before: %.2f mb\n", memory_get_usage(true) / 1024 / 1024);
for ( $i = 0; ++$i < 100000; )
{
	$order = new Order;
	$orders[] = $order;
}
printf("Mem after: %.2f mb\n\n", memory_get_usage(true) / 1024 / 1024);

unset($orders, $i);
$orders = [];

printf("Test2\nMem before: %.2f mb\n", memory_get_usage(true) / 1024 / 1024);
for ( $i = 0; ++$i < 100000; )
{
	$order = new Order;
	$orders[] = $order;
}
printf("Mem after: %.2f mb\n\n", memory_get_usage(true) / 1024 / 1024);

unset($orders, $i);
$orders = [];

printf("Test3\nMem before: %.2f mb\n", memory_get_usage(true) / 1024 / 1024);
for ( $i = 0; ++$i < 100000; )
{
	$order = new Order;
	
	$order->id     = '123';
	$order->number = '12345';
	$order->date   = '123456';
	
	$orders[] = $order;
}
printf("Mem after: %.2f mb\n\n", memory_get_usage(true) / 1024 / 1024);

unset($orders, $i);

printf("Mem after: %.2f mb\n\n", memory_get_usage(true) / 1024 / 1024);

Expected result:
----------------
no memory leaks

Actual result:
--------------
PHP 5.4.17-1~dotdeb.0 Linux

Test1
Mem before: 0.25 mb
Mem after: 16.25 mb

Test2
Mem before: 4.75 mb
Mem after: 16.25 mb

Test3
Mem before: 5.00 mb
Mem after: 24.25 mb

Mem after: 5.25 mb