Index: src/wp-admin/js/theme.js
===================================================================
--- src/wp-admin/js/theme.js	(revision 37433)
+++ src/wp-admin/js/theme.js	(working copy)
@@ -979,7 +979,13 @@
 		this.liveThemeCount = this.collection.count ? this.collection.count : this.collection.length;
 		this.count.text( this.liveThemeCount );

-		this.announceSearchResults( this.liveThemeCount );
+		/*
+		 * In the Theme Installer the Themes count is already announced
+		 * because `announceSearchResults` is called on `query:success`.
+		 */
+		if ( ! themes.isInstall ) {
+			this.announceSearchResults( this.liveThemeCount );
+		}
 	},

 	// Iterates through each instance of the collection
@@ -1319,6 +1325,8 @@
 		'keyup': 'search'
 	},

+	searchTerms: '',
+
 	// Handles Ajax request for searching through themes in public repo
 	search: function( event ) {

@@ -1340,6 +1348,14 @@
 	doSearch: _.debounce( function( value ) {
 		var request = {};

+		// Don't do anything if the search terms haven't changed.
+		if ( this.searchTerms === value ) {
+			return;
+		}
+
+		// Updates searchTerms with the current search terms.
+		this.searchTerms = value;
+
 		request.search = value;

 		// Intercept an [author] search.