Merge branch 'wip-MDL-34404-m24' of git://github.com/samhemelryk/moodle

lib/javascript-static.js

@@ -716,7 +716,13 @@ M.util.get_string = function(identifier, component, a) {
         // creating new instance if YUI is not optimal but it seems to be better way then
         // require the instance via the function API - note that it is used in rare cases
         // for debugging only anyway
-        var Y = new YUI({ debug : true });
+        // To ensure we don't kill browser performance if hundreds of get_string requests
+        // are made we cache the instance we generate within the M.util namespace.
+        // We don't publicly define the variable so that it doesn't get abused.
+        if (typeof M.util.get_string_yui_instance === 'undefined') {
+            M.util.get_string_yui_instance = new YUI({ debug : true });
+        }
+        var Y = M.util.get_string_yui_instance;
     }
 
     if (!M.str.hasOwnProperty(component) || !M.str[component].hasOwnProperty(identifier)) {