05 / PERCEIVED PERFORMANCE
Optimistic UI
The problem
After you click, nothing happens until the server replies, so the interface feels frozen and unresponsive.
The solution
Update UI immediately. Synchronize server afterward.
Experiment
Task: Like the post and observe response timing.
NAIVE
clientidle
serveridle
THOUGHTFUL
clientidle
serveridle
Play with the values
1500ms
0.15
How it works
Seen in
Like buttons
The heart fills instantly on tap while the server request runs in the background.
Save toggles
Bookmark or save state flips immediately so the action feels acknowledged.
Star ratings
Stars highlight on click before the rating is persisted, with rollback if the request fails.
Follow buttons
Follow state updates at once; a failed request quietly reverts instead of blocking the UI.