Our team has been evaluating alternative web server software, and software stacks to deliver better performance. Delivering increased performance, without having any negative side effects requires some effort. Some alternative web servers don't fully support all of the features of Apache, or implement them in a different manner. Our goal is to deploy a system which is 100% compatible with your existing site.
As many are aware, we do have some servers running Litespeed Enterprise. Litespeed is an excellent product, and does deliver better performance than Apache. However, some customers do experience minor issues at times with how it handles .htaccess settings. Though, with the most recent release we haven't had any new reports of that. Litespeed delivers both improved static content serving, and PHP.
We've also been evaluating a custom built stack, that consists of a modified Apache 2.2 server, running nginx as a reverse proxy in front of it. nginx is an extremely lightweight, high performance web server that is used by some of the largest sites in the world. It's one of the fastest static content servers out there. By running it in a reverse proxy, we can utilize Apache on the back-end to process your PHP pages, while utilizing nginx to serve the static content or media files. This configuration allows Apache to focus on the dynamic work, and since it's Apache, it's 100% compatible with .htaccess settings. While nginx will do static content serving, which is the bulk of the web server traffic.
At this stage, our team hasn't decided which route we'll adopt. Both methods have their pros and cons. Stay tuned to find out what we decide.