Ticket #13091: 13091.patch

comment.php

@@ -1495 +1495 @@
         $new = (int) $wpdb->get_var( $wpdb->prepare("SELECT COUNT(*) FROM $wpdb->comments WHERE comment_post_ID = %d AND comment_approved = '1'", $post_id) );
         $wpdb->update( $wpdb->posts, array('comment_count' => $new), array('ID' => $post_id) );
 
-        if ( 'page' == $post->post_type )
-                clean_page_cache( $post_id );
-        else
-                clean_post_cache( $post_id );
+        if($new != $old) { /* if the comment count has changed */
+                if ( 'page' == $post->post_type )
+                        clean_page_cache( $post_id );
+                else
+                        clean_post_cache( $post_id );
 
-        do_action('wp_update_comment_count', $post_id, $new, $old);
-        do_action('edit_post', $post_id, $post);
+                do_action('wp_update_comment_count', $post_id, $new, $old);
+                do_action('edit_post', $post_id, $post);
+        }
 
         return true;
 }