Getting collection calls access_restriction which is not properly cached.

Remove use of cache in AccessRestriction and use instance memory cache instead.
Beware static keyword declares variable static for the class, not the instance

lib/classes/appbox.php

@@ -335,7 +335,7 @@ class appbox extends base
     /**
      * @return AccessRestriction
      */
-    private function getAccessRestriction()
+    public function getAccessRestriction()
     {
         return $this->app['conf.restrictions'];
     }