The SitePoint PHP blog has posted the latest tutorial in their series creating a simple image gallery application with a focus on performance. In this latest article they cover the use of Varnish for output and page caching.

According to Pingdom.com, a company focused on web performance, in 2012 Varnish was already famous among the world’s top websites for its capacity to speed up web delivery.

[...] Although there are other solutions that also shine, Varnish is still a go-to solution that can dramatically improve website speed, reduce the strain on the web application server’s CPU, and even serve as a protection layer from DDoS attacks. KeyCDN recommends deploying it on the origin server stack.

Varnish can sit on a dedicated machine in case of more demanding websites, and make sure that the origin servers aren’t affected by the flood of requests.

The article starts by explaining a bit about how Varnish (and caching in general) works to help improve the performance for the end user. It also goes through some of the basics feature of Varnish including threaded executions, extensibility and its domain-specific language. The tutorial then walks you through the installation of Varnish on a linux-based machine and shares some example stats showing the difference between normal requests and when Varnish is enabled for the image gallery application.