Page Speed Analysis
Short answer
Measure load speed and Core Web Vitals, and see the biggest savings — including missing text compression.
What It Does
Runs a real Lighthouse audit on your URL via Google's PageSpeed Insights API, returning Core Web Vitals (LCP, INP, CLS), performance score, and a prioritized list of opportunities. Includes both lab data (controlled run) and field data (real-user CrUX 28-day window) when available.
Why It Matters
Google says Core Web Vitals are used by its ranking systems, although great page experience does not outweigh relevant content. Speed also shapes what visitors do: slow pages lose people before they read a word. Fixing your slowest templates helps every page built on them.
How It Works
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Enter your page URL and choose mobile or desktop strategy
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We trigger a real Lighthouse run via Google's PageSpeed Insights API
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Capture lab metrics (LCP, FCP, CLS, TBT, Speed Index) plus field data from CrUX (INP, LCP, CLS, FCP, TTFB) when available
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Return a numeric score, the full Core Web Vitals picture, and ranked opportunities such as unused JavaScript or missing text compression
Sample input + output
url: https://rankproof.eu/tools strategy: mobile
Lab test (mobile) Performance score: 92/100 Largest Contentful Paint: 1.4 s Total Blocking Time: 18 ms Cumulative Layout Shift: 0.02 First Contentful Paint: 0.8 s Real visitors (last 28 days): not enough data yet Top opportunities: Reduce unused JavaScript −0.4 s Enable text compression −0.2 s
Who Uses This
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Performance Engineer
Re-run the check after every release and track the Core Web Vitals trend by hand to catch regressions early.
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E-commerce Manager
Audit product pages monthly — every 100ms cut from LCP is measurable revenue on high-traffic categories.
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SEO Specialist
Identify the worst-performing top 20 pages and prioritize them for the dev team's next sprint.
Frequently Asked Questions
Lab data vs field data — what's the difference?
Lab data is one synthetic run in a controlled environment. Field data (CrUX) is real-user metrics aggregated over 28 days. Google ranks based on field data; lab data is the iteration tool.
Why does my score change between runs?
Lighthouse has natural variance (CPU contention, network jitter). Google's ranking signal is field data, which averages thousands of real users — far more stable.
What CWV thresholds should I target?
Good = LCP ≤ 2.5s, INP ≤ 200ms, CLS ≤ 0.1. Anything above is "Needs Improvement" or "Poor" and counts against you.
Mobile or desktop strategy?
Mobile-first index = mobile is what Google uses for ranking. Always optimize mobile first; desktop is the secondary check.
Does poor Core Web Vitals hurt rankings?
It can. Google uses Core Web Vitals in its ranking systems, but relevance comes first — a fast page will not outrank a much more relevant one.
Does it check text compression?
Yes. If the page's HTML, CSS or JavaScript is served without compression such as gzip or Brotli, "Enable text compression" appears among the opportunities with the time it would save.