Verify external caches are working properly

https://www.drupal.org/node/2364011

(worth also checking https://www.drupal.org/node/2364011#comment-9291895)
This is just markup. It's merely informative. I'd like to keep it.

![restful rest performance 2014-12-02 08-27-05](https://cloud.githubusercontent.com/assets/1140906/5259199/06052a0e-79fd-11e4-9dc0-69d81f99039f.png)