Index: wp-includes/nav-menu.php
===================================================================
--- wp-includes/nav-menu.php	(revision 22397)
+++ wp-includes/nav-menu.php	(working copy)
@@ -347,11 +347,12 @@
 		'post_type' => 'nav_menu_item',
 	);
 
-	if ( $menu_id && ! is_object_in_term( $menu_item_db_id, 'nav_menu', (int) $menu->term_id ) )
+	$update = 0 != $menu_item_db_id;
+
+	// Only set the menu term if it isn't set to avoid unnecessary wp_get_object_terms()
+	if ( $menu_id && ( ! $update || ! is_object_in_term( $menu_item_db_id, 'nav_menu', (int) $menu->term_id ) ) )
 		$post['tax_input'] = array( 'nav_menu' => array( intval( $menu->term_id ) ) );
 
-	$update = 0 != $menu_item_db_id;
-
 	// New menu item. Default is draft status
 	if ( ! $update ) {
 		$post['ID'] = 0;