Performance metric
What is TTI?
Time to Interactive is a Lighthouse lab metric that estimates when a page is visually loaded and reliably responsive. It is less central than INP today, but it can still highlight heavy JavaScript.
Plain-English version
When the page becomes fully usable.
Target
Under 3.8s
TTI thresholds
Use thresholds as a triage tool. Field data matters most when there is enough real Chrome traffic for the page.
Good
≤ 3.8s
Needs work
3.8–7.3s
Poor
> 7.3s
Why it matters
What a visitor feels when TTI is bad.
Why TTI matters
TTI helps explain pages that look ready before they actually respond. That gap frustrates visitors because the interface appears usable but ignores input.
What a poor result usually means
A poor TTI usually means JavaScript keeps the main thread busy after content appears, often because of large bundles, hydration, analytics, ads, or widgets.
nimo audit lens
How nimo reads TTI in an audit.
The glossary explains the metric. The free audit checks the page, separates field data from lab diagnostics, and points at the first review step.
How nimo interprets it
nimo treats TTI as a legacy lab clue for pages that look loaded before they are reliably usable.
Source to trust first
Use Lighthouse TTI and TBT as debugging clues. Use INP field data when deciding whether users feel the delay.
Evidence to inspect
- Main-thread quiet window after visible content appears.
- Long tasks during hydration or startup.
- Third-party widgets that keep the page busy.
- Whether INP data confirms an interaction problem.
First fix to review
Reduce startup and hydration JavaScript that runs after visible content appears.
How to validate
Rerun Lighthouse and compare TTI and TBT, then confirm INP field status or interaction tests before prioritizing more TTI work.
What to fix first
Do not chase the score. Fix the bottleneck.
The right fix depends on the metric, the page template, and whether the issue appears in real visitor data.
- Reduce JavaScript required for the first page view.
- Defer widgets, analytics, and non-critical third-party scripts.
- Break up long tasks during hydration and startup.
- Prefer interaction-level diagnostics when INP data is available.
- Check whether the page is slow only in lab data or also for real users.
How nimo helps
Run the free audit, then ask: “Why does my page take so long to become interactive?”
nimo treats TTI as a lab diagnostic and pairs it with INP so you know whether users are truly feeling the delay.
No signup needed. Takes about 30 seconds.