As far as I know, I'm the only conscious being in this simulated universe and nothing else is rendered or precisely computed until I observe it. What appears to be fundamental laws of the universe could very well be high level abstractions that are run at "good enough" quality for my personal experience to be believable, and only have more dedicated and precise simulations when I'm measuring the data personally. And even that could be unreliable. When you live in a system that controls everything, can you trust even your basic observations?
Also, if the fundamental laws of physics are determined by a simulation, why would anyone assume that the operators of the simulation would copy their own laws of physics exactly?