Don't miss to click around a little (but probably not too much) on the D forum. It's super fast, but also somewhat annoying (at least in chrome) since it flashes when reloading. Is there a write up somewhere of the stack (etc.) behind it?
To my memory it's basically generated static content. That's why it handles high load with such grace, and is so fast even on the slowest devices. I don't know the complexities behind that, but damn, I wish more sites did it.