The site is actually slower today than it will be in the near future. Today it is indexing search terms, emailing a zillion notifications, and doing a bunch of extra one-time stuff. I can't say it will be super zippy all the time, but it will be faster than the slow times today, most of the time.
Also, this is a starting point. There are quite a few things I am not satisfied with currently, and we will be tweaking them in the days and weeks to come. A lot of them involve the layout and wasted space. For example I was noticing that there is a ton of extra width in the username/avatar part of the postbit. When we get that narrowed down some, it will add significantly to the amount of space available for post content. And obviously, there is a lot of vertical space taken up that I think can be condensed down to get more content on the page. We will be working on that.