Time to Interactive
Also called: TTI, Time-to-Interactive
Time to Interactive (TTI) is a lab performance metric that measures the time from when a page starts loading until it can reliably respond to user input quickly. Google deprecated it and removed it from Lighthouse in version 10 (2023), pointing people to Total Blocking Time and Interaction to Next Paint instead.
TTI came from the synthetic (lab) side of performance testing, not from real users. It was never a Core Web Vitals metric, and as of 2026 it no longer factors into a Lighthouse performance score at all.
How TTI was measured
Lighthouse computed TTI by starting at First Contentful Paint, then scanning forward for a quiet window of at least five seconds with no long tasks (over 50ms) and no more than two in-flight network requests. It then walked backward to the end of the last long task before that window. The target was under 5 seconds on median mobile hardware.
The problem was variance. A single stray network request or one late long task could shove the quiet window far to the right, so TTI swung wildly between runs on the same page. Google removed it from the Lighthouse report and score in version 10 (Chrome 112, 2023) and reassigned its 10% weight to Cumulative Layout Shift. The raw value still lives in the Lighthouse JSON at weight 0 for old CI assertions, but it no longer shapes anything you are scored on.
What took its place: Total Blocking Time (TBT) as the lab proxy for a congested main thread, and Interaction to Next Paint (INP) as the field metric that actually counts in Core Web Vitals. If you still see TTI in a legacy audit or a third-party tool, read it as a rough “too much JavaScript” flag, then act on TBT and INP.
How it affects your traffic
TTI no longer moves rankings on its own, but the root cause it used to flag (JavaScript blocking the main thread) still drives Interaction to Next Paint, which is a live Core Web Vitals metric Google measures on real visitors. Sluggish interactivity frustrates mobile users and can hold back rankings on slower devices. Our Technical SEO work profiles main-thread blocking, trims and defers scripts, and pushes TBT and INP into the green so pages feel responsive, not just "loaded."
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