I don't have a source, but back when ARM Zen was going to be a thing (hopefully it still will), AMD was claiming a 10% uplift in performance over x64. That str

I don't have a source, but back when ARM Zen was going to be a thing (hopefully it still will), AMD was claiming a 10% uplift in performance over x64. That struck me as one of the few apples to apples comparisons ever of the instruction sets at the high end, from a party not really incentivized to bend the truth one way or another. But it could have easily come from something like the relaxed memory model, or they could have just been overly optimistic. The chip was cut after all.