Index: wp-admin/js/customize-widgets.js
===================================================================
--- wp-admin/js/customize-widgets.js	(revision 40900)
+++ wp-admin/js/customize-widgets.js	(working copy)
@@ -53,7 +53,8 @@
 
 		// Controls searching on the current widget collection
 		// and triggers an update event
-		doSearch: function( value ) {
+		doSearch: _.debounce( function( value ) {
+			var options = {};
 
 			// Don't do anything if we've already done this search
 			// Useful because the search handler fires multiple times per keystroke
@@ -75,8 +76,9 @@
 					widget.set( 'search_matched', true );
 				} );
 			}
-		},
 
+		}, 500 ),
+
 		// Performs a search within the collection
 		// @uses RegExp
 		search: function( term ) {
Index: wp-includes/class-wp-customize-widgets.php
===================================================================
--- wp-includes/class-wp-customize-widgets.php	(revision 40900)
+++ wp-includes/class-wp-customize-widgets.php	(working copy)
@@ -770,7 +770,7 @@
 				'saveBtnLabel'     => __( 'Apply' ),
 				'saveBtnTooltip'   => __( 'Save and preview changes before publishing them.' ),
 				'removeBtnLabel'   => __( 'Remove' ),
-				'removeBtnTooltip' => __( 'Trash widget by moving it to the inactive widgets sidebar.' ),
+				'removeBtnTooltip' => __( 'Remove widget by moving it to the inactive widgets list: your widget settings/content will be preserved.' ),
 				'error'            => __( 'An error has occurred. Please reload the page and try again.' ),
 				'widgetMovedUp'    => __( 'Widget moved up' ),
 				'widgetMovedDown'  => __( 'Widget moved down' ),