OO in PHP5.0 - Referencing Object or not?!

hello together look at the following code ... why is this .. -- code start

       if ( is_object($this->getManagerObject()->getDataFieldManager()) )
       {
           for ( $j = 0; $j < $this->getManagerObject()->getDataFieldManager()->getCount(); $j++ )
           {
               if ( $this->getManagerObject()->getDataFieldManager()->m_objData[$j]['GI_ID'] == $this->getID() )
               {
                   $l_objDataField = new GalleryDataField(
                       $this->getManagerObject()->getDataFieldManager(),
                       $this->getManagerObject()->getDataFieldManager()->m_objData[$j]
                   );

                   $l_objDataField->generateXML();

                   $l_strData .= $l_objDataField->getXML();

                   unset($l_objDataField);
               }
           }
       }

-- code end .. about 2 seconds slower than this .. -- code start

       $l_objDataFieldManager = $this->getManagerObject()->getDataFieldManager();

       if ( is_object( $l_objDataFieldManager ) )
       {
           for ( $j = 0; $j < $l_objDataFieldManager->getCount(); $j++ )
           {
               if ( $l_objDataFieldManager->m_objData[$j]['GI_ID'] == $this->getID() )
               {
                   $l_objDataField = new GalleryDataField(
                       $l_objDataFieldManager,
                       $l_objDataFieldManager->m_objData[$j]
                   );

                   $l_objDataField->generateXML();

                   $l_strData .= $l_objDataField->getXML();

                   unset($l_objDataField);
               }
           }
       }

       unset($l_objDataFieldManager);

-- code end ??? i just read, that objects in php 5 automatically returned as reference? in my code it doesn't seems like that!! ps: variable m_objData contains a lot of data from a mysql db thanks for answers.