I though FEMP was the most popular setup.
https://www.rootbsd.net/kb/330/Installing-Nginx-MySQL-56-PHP-56-on-FreeBSD-103.html
It will really depend on the web application. You can have the fastest setup in the world but a crappy web application is going to slow the whole thing down to a crawl. I would also suggest not adding complexity like Varnish or Memcached until you actually need it. Adding complexity will make things more error-prone (more places for mistakes to creep in). You could end up with a bigger management load without gaining anything (which would be a waste of your time).But laughs aside is this still an mega fast free setup?