No. Proxy cache was our first approach. Proxy cache solves the performance problem. There's also the issue of code mess in most Wordpress themes. We used Pagespeed as reference and our score -with- proxy cache was about 60. Once we re-wrote the theme in our static site framework, the Pagespeed score was 95. Could I have achieved the same with PHP? Probably. The biggest problem is Wordpress doesn't have an MVC like framework which makes it easy to write messy code even for experienced developers. Plus, Elixir, the language I used is miles ahead of PHP.

Right now, we have MVC down to the theme level. It helps write cleaner code and writing integrations to our site much much faster. There's tons of integrations that large media sites actually use. Eg. ad server related, tracking related, etc.