Waiting for Drupal's menu rebuild to happen every time I look at the modules page makes me want to torture kittens.

There are two issues here. First, the performance of rebuilding the menu is horrible: #302638: No-op and slow queries during menu rebuild Second, I challenge the assumption that viewing the modules page is the right time to rebuild the router table. After all, how could this NOT be slow when simply getting the form does this?

function system_modules($form_state = array()) {
  // Clear all caches.
  registry_rebuild();
  drupal_theme_rebuild();
  node_types_rebuild();
  cache_clear_all('schema', 'cache');
  // Get current list of modules.
  $files = system_get_module_data();

I suggest we move all that crud to the submit handler.