A colleague of mine tells a story about being harangued during an outage because his system was too slow and to do something about it, where the punchline is that doing something about it would mean either increasing the speed of light or reducing the distance or both. I thought it was a joke until the other day when I myself saw one of these design requirements come through.
The designer expects a 10ms round-trip. The end-points are roughly 5000 miles away. Now if you’re not laughing already, I’ll do the back of the envelope for you- The speed of light in a vacuum is 1,079,252,848.8 km per second. The distance is approximately 8000 km. This works out to just a little under 16ms round-trip before considering that data networks are slower than light, that the network and application protocols involve several round-trips and that the application on each end must process the data.
A teammate politely pointed them in the right direction.