A factory-telemetry simulator that replays four hours in 15,000-millisecond steps and again in 150,000-millisecond steps must produce a byte-identical event list, or every calibrated OEE band is only true at the speed you happened to demo it — a discrete-event scheduler makes the tick size irrelevant by design, and a test proves it rather than assuming it.
Your scale ceiling is an arithmetic result, not a feeling — throughput is concurrency over latency, and a CPU-bound box tops out at cores divided by CPU-seconds per request. Most systems fall over at a small fraction of that number because of coordination and copies, not because the machine is small.