Show me a production website that does not use things like Caching, CDN's to serve static content or other optimizations to enhance performance It's the same as any other public facing service. I don't know what you are yapping about.

Thank you, was going to say this but you beat me to it. What type of web development is this guy using that he considers using a CDN a no-go?

Mind you when I made my original statement I had in mind websites that handle millions of monthly uniques and are somewhat dynamic in terms of the content they publish - for smaller scales WP needs basically nothing else and just works, but this scenario is really quite easy with WP if you employ common caching strategies, and is probably impossible with the typical "I wrote this script that generates static HTML last weekend and therefore it's a revolution in CMSes" solution