But you will get fewer per step, which is my point. If you get fewer, then you'll need to run the simulation for longer, thus negating any savings.
But you're right in that you'd get different effects, because effects like gravity depend on the distance between objects, which is invariant on the speed of light, so a "human" in a universe where c is halved but everything else is the same wouldn't just be larger, but be completely different.
But if you're changing the behavior of the simulation then it's not even an optimization anymore. You just changed the simulation. It may as well be something entirely different.
But you're right in that you'd get different effects, because effects like gravity depend on the distance between objects, which is invariant on the speed of light, so a "human" in a universe where c is halved but everything else is the same wouldn't just be larger, but be completely different.
But if you're changing the behavior of the simulation then it's not even an optimization anymore. You just changed the simulation. It may as well be something entirely different.