WordPress is usually praised for usability, not performance. To make WordPress faster and more efficient, you need a caching plugin like W3 Total Cache. It caches your pages in static files, caches queries and results in memcache, and rewrites css, images, and js to CDN paths if you have a provider. In front of this, I would have Varnish cache as much as possible in memory, for even faster access. W3 Total cache can even invalidate your Varnish cache when pages are updated.