PHP Timeout in token.module

I've received a PHP Maximum Execution Timeout when trying to edit a node. The timeout is 300 sec (5 min).

The error has occured at various points but most commonly on line 1220 of token.module (7.x-1.5) which is inside the token_menu_link_load_all_parents function:

function token_menu_link_load_all_parents($mlid) {
  $cache = &drupal_static(__FUNCTION__, array());

  if (!is_numeric($mlid)) {
    return array();
  }

  if (!isset($cache[$mlid])) {
    $cache[$mlid] = array();
    $plid = db_query("SELECT plid FROM {menu_links} WHERE mlid = :mlid", array(':mlid' => $mlid)\
)->fetchField();
    while ($plid && $parent = token_menu_link_load($plid)) {
      $cache[$mlid] = array($plid => $parent['title']) + $cache[$mlid]; // Line #1220
      $plid = $parent['plid'];
    }
  }

  return $cache[$mlid];
}

This site has a very large and deeply nested Main Menu. I'm unsure at this time what is causing the failure. Clearing caches has not affected performance on this issue.