Warning about the use of the router table being used for generating links

With a discussion with pwolanin, a contributor to the new Drupal menu system in v6, he gave very strong warnings about using the router table to generate links. For example "categories/234/34/344/33/4" type item as a callback for the view/term page. Namely speed and memory issues

Rather he say it was best to generate the single callback "categories/%" and then using taxonomy_hook or a custom callback to generate the menu items using menu_link_save. I am using the module in a very modified form, the refactoring that I have used, is similar to this: (Not runnable, I simply cut out the extra bits of code during the post)

<?php
  // create single callback and using wildcard loader to preload the vocab
  $path =  variable_get('taxonomy_menu_display_page', 'category');
  $arg_pos = count(explode('/', $path));
  $items[$path . '/%taxonomy_vocabulary'] = array(
     'title' => t($path),
     'page callback' => '_taxonomy_menu_general_menu_page',
     'page arguments' => array($arg_pos),
     'access arguments' => array('access content'),
     'file' => 'taxonomy_menu.page.inc',
  );

?>

and generating the links using:

<?php

/**
 * Mine is modified to be vocab specific. I've cut out most of this
 */
function taxonomy_menu_create_menu_links() {
  // delete the old menu items for this $vocab
  $path =  variable_get('taxonomy_menu_display_page', 'category');
  db_query("DELETE FROM {menu_links} WHERE module = 'taxonomy_menu'");

  // as per the normal module, but generate menu item rather than router link
  $tree = taxonomy_get_tree($vocab->vid);
  $old_depth = -1;
  $old_path = $path;
  foreach ($tree as $index => $term) {
    if ($term->depth <= $old_depth) {
      $slashes_to_remove = $old_depth - $term->depth + 1;
      for ($i = 0; $i < $slashes_to_remove; $i++) {
        $old_path = substr($old_path, 0, strrpos($old_path, '/'));
      }
    }
    $path       = $old_path .'/'. $term->tid;
    $old_depth  = $term->depth;
    $old_path   = $path;
    $num = taxonomy_term_count_nodes($term->tid);
    if (variable_get('taxonomy_menu_hide_empty', FALSE) == FALSE or $num != 0) {
      $name = t($term->name);
      if (variable_get('taxonomy_menu_display_num', FALSE) == TRUE) {
        $name .= ' ('. $num .')';
      }
      $item = array(
        'link_title'  => $name,
        'link_path'   => $path,
        'router_path' => $router_path,
        'weight'      => $term->weight,
        'menu_name'   => 'navigation',
        'module'      => 'taxonomy_menu', // used as a hook for delete, the ones in the hook_menu as linked to system
      );

      menu_link_save($item);
    }
  }
} 
?>

If you run "menu_link_save" during rebuild menus / flush cache, the install will crash due to recursion. That was fun debugging :) Thus the second function needs to be decoupled from the hook_menu. My hacked version simply appends it with a shut-down function. taxonomy_hook and maybe an admin link to regenerate menu items would be the best place.

Hope this helps / makes sense.