TTI
TTI is a lab metric estimating when a page becomes reliably interactive. It’s not a CWV metric but helps diagnose load-time JS blocking.
Definition
TTI (Time to Interactive) estimates how long it takes for a page to become reliably interactive, commonly shown in Lighthouse-type lab tools. It’s not a Core Web Vitals metric, but it helps diagnose load-time JS blocking and long-task pressure.
Why it matters
- Diagnoses load-time interactivity issues (main-thread blocking)
- Often correlates with TBT/INP problems
- Guides bundle splitting and third-party script strategy
How to implement
- Split bundles, defer non-critical JS, reduce third-party cost
- Reduce long tasks (TBT) to free the main thread
- Prioritize critical above-the-fold interactivity first
FAQ
Common questions about this term.