Index: src/wp-includes/comment.php
===================================================================
--- src/wp-includes/comment.php	(revision 37595)
+++ src/wp-includes/comment.php	(working copy)
@@ -1588,6 +1588,9 @@
 	if ( $comment_approved == 1 ) {
 		wp_update_comment_count( $comment_post_ID );
 	}
+
+	clean_comment_cache( $id );
+
 	$comment = get_comment( $id );
 
 	// If metadata is provided, store it.
@@ -1607,8 +1610,6 @@
 	 */
 	do_action( 'wp_insert_comment', $id, $comment );
 
-	wp_cache_set( 'last_changed', microtime(), 'comment' );
-
 	return $id;
 }
 
Index: src/wp-includes/load.php
===================================================================
--- src/wp-includes/load.php	(revision 37595)
+++ src/wp-includes/load.php	(working copy)
@@ -477,7 +477,7 @@
 
 	if ( function_exists( 'wp_cache_add_global_groups' ) ) {
 		wp_cache_add_global_groups( array( 'users', 'userlogins', 'usermeta', 'user_meta', 'useremail', 'userslugs', 'site-transient', 'site-options', 'site-lookup', 'blog-lookup', 'blog-details', 'rss', 'global-posts', 'blog-id-cache', 'networks', 'sites' ) );
-		wp_cache_add_non_persistent_groups( array( 'comment', 'counts', 'plugins' ) );
+		wp_cache_add_non_persistent_groups( array( 'counts', 'plugins' ) );
 	}
 }
 
Index: src/wp-includes/ms-blogs.php
===================================================================
--- src/wp-includes/ms-blogs.php	(revision 37595)
+++ src/wp-includes/ms-blogs.php	(working copy)
@@ -766,7 +766,7 @@
 			} else {
 				wp_cache_add_global_groups( array( 'users', 'userlogins', 'usermeta', 'user_meta', 'useremail', 'userslugs', 'site-transient', 'site-options', 'site-lookup', 'blog-lookup', 'blog-details', 'rss', 'global-posts', 'blog-id-cache', 'networks', 'sites' ) );
 			}
-			wp_cache_add_non_persistent_groups( array( 'comment', 'counts', 'plugins' ) );
+			wp_cache_add_non_persistent_groups( array( 'counts', 'plugins' ) );
 		}
 	}
 
@@ -837,7 +837,7 @@
 			} else {
 				wp_cache_add_global_groups( array( 'users', 'userlogins', 'usermeta', 'user_meta', 'useremail', 'userslugs', 'site-transient', 'site-options', 'site-lookup', 'blog-lookup', 'blog-details', 'rss', 'global-posts', 'blog-id-cache', 'networks', 'sites' ) );
 			}
-			wp_cache_add_non_persistent_groups( array( 'comment', 'counts', 'plugins' ) );
+			wp_cache_add_non_persistent_groups( array( 'counts', 'plugins' ) );
 		}
 	}