To speak nothing of loading up a php-fpm thread, parsing a minimum of 3300 lines of php code before passing the result back. I don't believe php does any code caching normally so that's a full parse each time (this is where APC/Xcache/Opcache/Ioncube come in). As opposed to a hash check on the url and a light disk hit to fetch the pregenerated file that's probably still in an OS ram cache. fastcgi_cache is pretty much guaranteed to win...I guess redis suffers a bit because of the extra tcp roundtrip.
you didn't try the best way to integrate Redis Cache with WordPress. There are three solutions to make this, that of Jim Westergreen is not the faster. Please, when you have free time, try that of Benjamin Adams.
With it, using Nginx + fastcgi cache + Redis Cache + Zend Opcache, my WordPress site (about 700kb), load below 250ms.
Have you a nice day