There are a lot of test and comparisons about Nginx vs Apache. And yes for static content because it is asynchronous, Nginx preforms better. What happens when you have PHP?
I have setup two servers with:
- Apache + PHP + APC + Varnish
- Nginx + PHP-FPM + APC + Varnish
Adding APC and Varnish as stages and it seems that in those conditions both Apache and Nginx are almost the same thing.
Actually I used them to server Wordpress documents, so MySQL was also involved, but the bottle neck was PHP, APC made a great job and with Varnish both setups fly.
Read the rest here: http://www.garron.me/linux/apache-vs-nginx-php-fpm-varnish-apc-wordpress-performance.html