I had another look at Tallinn's presentation, and it seems he is rather vague on this... rather difficult to know what computing designs super-intelligences would come up with! However, presumably they would use quantum computers to maximize the number of simulations they could create, which is how they could get branch-points every simulated second (or even more rapidly). Bostrom's original simulation argument provides some lower bounds - and references - on what could be done using just classical computation.