I've heard great things about HHVM, so I've setup a copy of WordPress blog (on another domain) with Nginx (with the Pagespeed module) and HHVM. Right now the benefits are obvious: on the same config, load times are between two and three times faster.
I'm trying to speed up things a little bit, and I've also installed Memcached and Batcache. I've installed the memcached package, copied object-cache.php (Pastebin) onto the root folder of the WordPress blog, and after that I've installed the Batcache plugin and copied the advanced-cache.php (Pastebin) file onto the wp-content folder. Also, I've included the line
in the wp-config.php file. It seems it doesn't work, though. If I quickly reload the page several times Batcache should show the cached page, but it doesn't. It's easy to check that by reloading (Cmd+R on Chrome on OS X) the page several times and then viewing the page's code. Under the
<head> section I should see some batcache stats, but they aren't there.
I wonder if someone could give me some hint on this.
On a side note, I don't know if I could add some other component in order to help the performance be even better. I'm thing about Varnish, but I'm not sure if it's just useless and it's just another way to the same I'm currently doing. Any other component there? (I'll test CDN for images, minifying js, etc and some other tricks as well, but I'm talking from the server perspective).