Laws of UX
Doherty Threshold
Productivity soars when response time is under 400ms. Interactions that feel instant maintain flow state. Use skeleton screens, optimistic UI, and progress indicators when latency exceeds this threshold.
In plain terms
If a screen responds in under about half a second, it feels instant and people stay focused. Show progress when it's slower.
Why this matters
Slow, unresponsive interfaces break concentration and frustrate everyone — and are especially disorienting for users with cognitive disabilities. Visible progress keeps people oriented and in control.