Thinkscape

# php -v
PHP 5.3.6 (cli) (built: Mar 17 2011 20:58:15)
Copyright (c) 1997-2011 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2011 Zend Technologies

# echo '<?php $s = array(); for($x=0;$x<1000;$x++){ $s[] = array("name"=>"Adam","age"=>35); }; echo memory_get_peak_usage(); ' | php
655040

# echo '<?php $s = array(); for($x=0;$x<1000;$x++){ $o = new ArrayObject; $o->name = "Adam";  $o->age = 35;  $s[] = $o;} echo memory_get_peak_usage(); ' | php
887984