Index: wp-includes/template-loader.php
===================================================================
--- wp-includes/template-loader.php	(revision 21499)
+++ wp-includes/template-loader.php	(working copy)
@@ -6,6 +6,16 @@
 if ( defined('WP_USE_THEMES') && WP_USE_THEMES )
 	do_action('template_redirect');
 
+/**
+ * Halt template load for HEAD requests. Performance bump by eliminating output
+ *
+ * @since 3.5.0
+ */
+if ( 'HEAD' === $_SERVER['REQUEST_METHOD'] && apply_filters( 'exit_on_http_head', true ) ) {
+    add_filter( 'wp_die_ajax_handler', '_scalar_wp_die_handler' );
+    wp_die();
+}
+
 // Process feeds and trackbacks even if not using themes.
 if ( is_robots() ) :
 	do_action('do_robots');