> Moreover, the ceiling you could get in boosting single-threaded performance with a perfect branch predictor (for conditional branches) over current state-of-t

> Moreover, the ceiling you could get in boosting single-threaded performance with a perfect branch predictor (for conditional branches) over current state-of-the-art is around 4%. No, actually having perfect branch prediction is a major blocker on performance even now, since it limits the useful size of the out-of-order reorder buffer.