[eluser]WanWizard[/eluser]
Try to understand how PHP, and CodeIgniter work.
In PHP5, all objects are assigned by reference. This means that although you see them when you access a Datamapper object, they are not copies, and don't take up memory.
CodeIgniter works by assigning all objects as singletons to $this, so a var_dump($this) will show you pages and pages of object information. All other objects that access CI ( either via an automatic mechanism or through get_instance() ) use references.
So obviously you'll see all this when you dump a Datamapper object. Because Datamapper accesses the database, language, and form validation libraries, which in turn have links to several other libraries.