getPerfMenu

    /**
     * 
     * Alternative and (will be) much faster menu generator to {@link ContentController::getMenu()}.
     * 
     * - Uses raw DataQuery, skipping most of the ORM's heavy lifting
     * - Doesn't require repeated calls to {@link Hierarchy::Children()}
     * - Still works with unmodified template logic that calls $Menu(1).
     SEE: Hierarchy::loadDescendantIDListInto()
     * 
     * @param int $level Menu level to return.
	 * @param array $filter
     * @return ArrayList
     * @todo Re-engineer ORM call as a SQLQuery because it's faster
     * @todo Weird shit going on when using Property names in templates within the loop = slows it right down
	 * @todo Add userland YML to allow SS to use getMenu() or getPerfMenu()
     */
    public function getPerfMenu($level = 1, $filter = array()) {
        // Get me all the pages - replace with non ORM query
		$filterOn = array("ShowInMenus" => 1);
		if($filter) {
			$filterOn = array_merge($filterOn, $filter);
		}
		
        $nodes = SiteTree::get()->filter($filterOn);
		$list = ArrayList::create($nodes->toArray());
        $tree = array();
		
        foreach($list as $node) {
            $childNodes = array();
            if($list->find('ParentID', $node->ParentID)) {
                $childNodes[][$node->ID] = $node;
            }
            
			// Apply child-nodes in logic, rather than in-template: Avoids unecessary ORM calls
            $node->LeafNodes = ArrayList::create($childNodes);
            $tree[$level][$node->ID] = $node;
        }
        
        $items = ArrayList::create($tree[$level]);
        return $items;
    }