Ticket #16894: 16894.5.diff

src/wp-includes/comment-functions.php

@@ -2365 +2365 @@
                 wp_cache_add($comment->comment_ID, $comment, 'comment');
 }
 
+/**
+ * Lazy load comment meta when inside of a `WP_Query` loop.
+ *
+ * @since 4.4.0
+ *
+ * @param null $check      The `$check` param passed from the 'pre_comment_metadata' hook.
+ * @param int  $comment_id ID of the comment whose metadata is being cached.
+ * @return null In order not to short-circuit `get_metadata()`.
+ */
+function wp_lazyload_comment_meta( $check, $comment_id ) {
+        global $wp_query;
+
+        if ( ! empty( $wp_query->comments ) ) {
+                // Don't use `wp_list_pluck()` to avoid by-reference manipulation.
+                $comment_ids = array();
+                foreach ( $wp_query->comments as $comment ) {
+                        $comment_ids[] = $comment->comment_ID;
+                }
+                update_meta_cache( 'comment', $comment_ids );
+        }
+
+        return $check;
+}
+
 //
 // Internal
 //

src/wp-includes/default-filters.php

@@ -200 +200 @@
 add_filter( 'pingback_ping_source_uri', 'pingback_ping_source_uri'            );
 add_filter( 'xmlrpc_pingback_error',    'xmlrpc_pingback_error'               );
 add_filter( 'title_save_pre',           'trim'                                );
+add_filter( 'get_comment_metadata',     'wp_lazyload_comment_meta',     10, 2 );
 
 add_filter( 'http_request_host_is_external', 'allowed_http_request_hosts', 10, 2 );