node_delete is very slow

I have a simple function that loops through and deletes nodes of a certain type. These nodes are custom CCK content types that also behave as categories. The content type isn't very complex... about 5 fields.

Here is my function:

function _delete_cities_submit() {
	
	$query = "select nid from node where type='content-city'";
	$results = db_query($query);
  while ($node = db_fetch_object($results)) {
  	node_delete($node->nid);
  	$output .= "deleted node " . $node->nid;
  }
  
  drupal_set_message($output);
	
}

The problem is that this function takes about 10 minutes to delete 300 nodes!!