Sometimes we need to serve files directly from application, especially when file access is restricted by account permissions. Using readfile() to achieve this can successfully kill our web server - even without huge load. To avoid performance problems we can use nginx X-Accel-Redirect feature, and serve files from application through nginx server.

He sets up an example situation - serving up gallery images for a basic site - and shows how to configure the nginx server with the "/gallery" directory and the PHP code you'll need to push the "X-Accel-Redirect" header along with the contents of the image.