Index: src/wp-includes/widgets.php
===================================================================
--- src/wp-includes/widgets.php	(revision 31940)
+++ src/wp-includes/widgets.php	(working copy)
@@ -211,9 +211,14 @@
 	 * @access private
 	 */
 	public function _register() {
-		$settings = $this->get_settings();
+		$settings = false;
 		$empty = true;
 
+		// Prefetch settings only for widgets that are used (whether active or inactive)
+		if ( is_active_widget( false, false, $this->id_base, false ) ) { 
+			$settings = $this->get_settings();
+		}
+
 		if ( is_array($settings) ) {
 			foreach ( array_keys($settings) as $number ) {
 				if ( is_numeric($number) ) {