Frontend & browser·Performance and Core Web Vitals
you showed a response to the click immediately, even though the real work took another second.
Perceived performance
Also calledresponsiveness feel
How fast the interface feels, which depends on immediate feedback and predictable progress rather than on total elapsed time. Acknowledging an interaction within about a hundred milliseconds is what makes it feel direct, regardless of when the work finishes. This is why optimistic updates, skeletons and progress that actually moves are worth more than a proportionally larger improvement in a backend timing.