It would depend on a high number of factors, wouldn't it? You'd need to consider the possibilities of solipsism and if everything is always loaded in, or if instead things are only in existence when looked at
For factors, choose the way that minimizes the size of the host machine, while keeping the result meaningful, e.g. each living human is a distinct interactive member.
Maybe the speed of light is the equivalent to how long it takes to load from storage
That would imply the computer we are simulated on is isomorphic to the 3D universe it is simulating, i.e. that if A and B are close in the simulation, the storage for A and B are physically close in the simulator, and that the storage moves as the objects move. Otherwise the speed of light would vary from a place to another.
None of that matters if the simulation only has access to simulated time--e.g. a vm with access to a clocksource but not a 'real' time one.
Computers have to run even when we're not looking at them, at the very least.