Remember that in Tallinn's analysis, post-singularity civilizations run a colossal number of pre-singularity simulations, with the number growing exponentially up to the singularity (basically they want to explore lots of alternate histories, and these grow exponentially).
What substrate are they running these simulations on?
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.
r/Fitness does a weekly "Moronic Monday", a judgment-free thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. I thought this seemed like a useful thing to have here - after all, the concepts discussed on LessWrong are probably at least a little harder to grasp than those of weightlifting. Plus, I have a few stupid questions of my own, so it doesn't seem unreasonable that other people might as well.