Two eras of computing, held to the same 400 millisecond standard.Stop blaming the model for slow AI. Use Doherty’s threshold as a guideline.Doherty’s threshold set the rules and has now moved from the answer to the acknowledgment. The fix is a week of front-end work and a definition of done, not cheaper inference.Productivity soars when a computer and its users interact at a pace — under 400 milliseconds — that ensures neither has to wait on the other. Below the threshold, work feels like a conversation; above it, each pause breaks the user’s train of thought and errors climb. — Walter DohertyAsk a product team why their AI feature feels slow and you get a shrug wrapped in a technical explanation.The model takes eight seconds.Inference is expensive.Everyone’s model is slow.Buried in the shrug is an assumption: that the 400 millisecond threshold belongs to green screens and the entire...