Question 1

What's the difference between field data and lab data?

Accepted Answer

Field data (Chrome UX Report) comes from real visitors who loaded the page over the last 28 days. Lab data comes from a single simulated Lighthouse run performed right now. Field data reflects real-world conditions; lab data is reproducible and useful for debugging a specific change.

Question 2

Why does my score differ between mobile and desktop?

Accepted Answer

Mobile scans simulate a mid-tier phone on a throttled connection, which is far stricter than desktop. Most sites score noticeably lower on mobile -that's expected and is exactly why Google evaluates mobile performance separately.

Question 3

How is the AI Fix-It Summary generated?

Accepted Answer

It rewrites the raw Lighthouse opportunities for your specific scan into prioritized, plain-English action items using an AI model, so you don't need to interpret audit jargon like 'eliminate render-blocking resources' yourself.

Question 4

Does this tool store my data?

Accepted Answer

Each scan is stored against the URL you tested (not against your identity) so the tool can show a score trend over time. No login is required and no personal data is collected.

Website Performance Tester

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