Well, the smart thing would be to store the data in normalized tables like your supposed to, and then denormalize it with a fast refreshed materialized view (or one that is updated on a schedule, depending on how stale data can be tolerated), or add the extra speed with a caching layer.

If your hitting flickr traffic, then you have some tough problems to solve, but I don't think starting your app with non-normalized data would be very smart!