According to a quick check the forum.dlang.org initial page view takes 200ms. ruby-forum takes 738ms. If you want to talk RUM/page load metrics forum.dlang.org takes 800ms for the load event to fire, the ruby forum takes 1.6s.

The individual posts load really quickly, but the main page doesn't (well not as fast as the other one mentioned). Either way, both are fast and I wish more websites were like this, not just forums!