The problem with this article is that he is testing as ONE ACTIVE USER, as if only one person was ever using digg at any given time. Of course the queries are going to return thousands of times faster. Try replicating digg's actual environment, which I know nothing of, but I know the site gets a ton of traffic and probably has between 10-50,000 users online at any given time.

Now run the same queries you were doing again on your test machine, but simulating 50K users online at once. Oh, and don't forget about thousands of writes per second, which was conveniently not part of this test. What's that you say? The performance is suddenly complete shit? Color me shocked.