The Doherty Threshold: IBM's 400ms UX latency rule modern OSes like Win11 still violate
lauriewired · x · 2026-11-11
Security researcher lauriewired argues UX latency is the most frustrating non-advancement in computing over the past 50 years.
- IBM found back in the 80s that user productivity rose exponentially as system response time dropped, defining the Doherty Threshold of 400ms — the maximum tolerable UX latency before interrupting user flow.
- Many modern operating systems (he calls out Windows 11) constantly violate it. The attached IBM chart shows transactions per user-hour exploding as response time drops from 1.5s toward 0.25s.
- Actionable advice for devs: add a "Doherty Threshold" check to your test suite; profiling tools plus modern AI models leave no excuse. For unavoidable stalls, use UX tricks to preserve the illusion of responsiveness.
- Counterintuitive punchline: vintage hardware feels immeasurably more responsive despite thousands of times less performance.
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