Drupal's regular menu system administration doesn't scale very well. This is due to the fact that for all node edit pages, node type edit pages and vocabulary edit pages (when Taxonomy Menu is active), Drupal loads all menu items from all menus in the system. For large amount of menu items, this slows down the system to an unusably slow speed, or even causes timeouts.

The Menuperformance-module fixes these issues by preventing Drupal from loading the complete set of menu items, and by loading only the required menu items to the form widgets.