The speed of light is not just fast. It is a hard ceiling. No information, no matter, no signal exceeds it, and the limit does not behave like a practical problem you could solve with more power. It behaves like a rule of the system. Push harder and you do not go faster; you gain mass and the cost of further acceleration climbs toward infinity. The universe enforces the cap absolutely.

A continuous, unconstrained reality has no obvious reason to impose a top speed. Newtonian physics did not require one. It was introduced because that is how the universe actually behaves — there is a maximum rate at which one part of reality can affect another.

A computed reality needs exactly this. A system that updates in discrete steps has a maximum distance information can travel per step. That is a frame cap. It is not a flaw; it is what keeps the system consistent and prevents any part from outrunning the rest's ability to update. Causality stays intact because nothing moves faster than the grid can resolve.

This is not a claim that the speed of light proves we are simulated. It is an observation that the cap exists, that it is enforced rather than merely approached, and that a maximum propagation speed is precisely the constraint a step-based reality would have. Reality has a refresh rate. The number is 299,792,458 metres per second.