Index: wp-includes/general-template.php
===================================================================
--- wp-includes/general-template.php	(revision 14421)
+++ wp-includes/general-template.php	(working copy)
@@ -554,8 +554,10 @@
 		$title = $title->display_name;
 	}
 	if ( !empty($author_name) ) {
-		// We do a direct query here because we don't cache by nicename.
-		$title = $wpdb->get_var($wpdb->prepare("SELECT display_name FROM $wpdb->users WHERE user_nicename = %s", $author_name));
+		if ( ( $user_id = wp_cache_get($author_name, 'userslugs') ) && ( $user = wp_cache_get($user_id, 'users') ) ) 
+			$title = $user->display_name; 
+		else 
+			$title = $wpdb->get_var($wpdb->prepare("SELECT display_name FROM $wpdb->users WHERE user_nicename = %s", $author_name)); 
 	}
 
 	// If there's a month