Performance of taxonomy_menu_form_alter()

This module implements hook_form_alter(), using it on only 1 form.
Hence, we have too many code running on all-but-one pages.

So, we should rename
from function taxonomy_menu_form_alter(&$form, &$form_state, $form_id) {
to function taxonomy_menu_form_taxonomy_form_vocabulary_alter(&$form, &$form_state, $form_id) {

P.S. this requires a cache flush to be effective.