This is a textbook for how to set up a high-traffic web site. It's remarkable because of the openness. I was surprised at how many Squid machines they're running, but really, that makes sense.
Apparently they didn't apply that recipe to this link.
Do you use the same level of infrastructure for your documentation server as you do for your 10's of millions of visitors / day production server?
Same level? Just use the same infrastructure (put the same caching Squid servers in front).