Dynamic Ctreeview Is Slow

I made a dynamic CtreeView by enabling the $processOutput of renderPartial, but Ctreeview needs a long time to display. anyone know it and how to fix ?

controller:


$this->renderPartial('_tree', array(), false, true);

view:


$this->widget('CTreeView',array('url' => array('ajaxFillTree'),

	'collapsed'=>true,

 	'animated'=>'fast',));