I wonder how much of the positive performance is just because we have not proved that some impossible case is really impossible and so we have if statements checking for a situation that mathematically cannot happen just out of caution. (note that in many cases we don't even have the theoretical tools to prove the code)

Though that makes non-memory safe code more reliable in the case of a bit flip. (this is not a serious advantage - only some bit flips can be prevented this way)