Wordpress Performance Comparison: Using Nginx, Apache, APC and Varnish in Different Scenarios
www.garron.me/en/linux/apache-vs-nginx-php-fpm-varnish-apc-wordpress-performance.html
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
I like to try to squeeze every drop of power from a server before upgrading it. Usually this is achievable tweaking configuration of the server.