Ask HN: How fast are your real time analytics?

According to 3D Developer John Carmack, "Human sensory systems can detect very small relative delays in parts of the visual or, especially, audio fields, but when absolute delays are below approximately 20 milliseconds they are generally imperceptible."

Source: http://www.altdevblogaday.com/2013/02/22/latency-mitigation-strategies/

So, do real-time stats really need to be realtime?