Try to run nginx + memcached as described here https://techblog.evo.pl/en/2009/03/21/how-to-boost-speed-up-your-typo3-website-with-nginx/
Above shows how TYPO3 is powered by nginx but you can adopt it to your needs. Model is very simple. Your application writes data to memcached and Nginx read directly from memcached. This is very fast and efficient way. You can also configure nginx to bypass memcached if request is POST or match each custom urls.
I am not wordpres expert but I am sure that wordpres can write data do memched also.
