Durations too long
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Rule · bucket: judgment · severity: note · detector: none · since: v0.1.0
Section: Things to avoid
Group: Motion

Forbidden:
  500ms+ on UI feedback

Instead:
  100–200ms for state change, up to 300ms for larger transitions. If it can be perceived as waiting, it is too slow.

**Scope: this is about motion that answers an input or carries a state change.** It is not a ceiling on every animation on the page. Slow decorative looping motion — see `P-13` — runs for seconds by design, and is not covered here. The reason the two differ is the reason the numbers differ: interaction motion sits between the user and their task, so it must get out of the way; ambient motion is never in the way, so speed would only make it noticeable.