Metrics
Time to Interactive (TTI)
Also: TTI
The time until the main thread is reliably free to handle user input.
Definition
TTI measures when a page becomes reliably interactive — main thread free, event handlers wired, no long tasks. Replaced by INP in Core Web Vitals but still used in Lighthouse and lab measurement. Long TTI signals heavy hydration cost or third-party JS bloat.
More in Metrics
Largest Contentful Paint (LCP)
The render time of the largest content element visible in the viewport.
Interaction to Next Paint (INP)
Worst-case latency between a user input and the next visual update.
Cumulative Layout Shift (CLS)
How much visible content unexpectedly shifts during a page lifetime.
Time to First Byte (TTFB)
The time between request and the first byte of response from the origin or CDN.
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