Page speed test
Measure load time, render blocking and Core Web Vitals.
In short
A page speed test loads a URL in a controlled environment and reports Core Web Vitals — Largest Contentful Paint, Cumulative Layout Shift and Interaction to Next Paint — alongside the render-blocking resources and payload weight that cause them.
What the Page speed test checks
- Largest Contentful Paint and what element triggers it.
- Cumulative Layout Shift and the nodes that move.
- Total transfer size split by resource type.
- Render-blocking scripts and stylesheets in the critical path.
- Compression, caching headers and image formats.
How to read your results
- LCP above 2.5 seconds is the single most common failing vital and is usually an unoptimised hero image or a blocking font.
- A layout shift score that only appears on mobile normally means an image or ad slot without reserved dimensions.
- A good lab score with poor field data means your real users are on slower networks or devices than the test.
Limitations of this tool
- Lab measurements are a single synthetic run and will not match field data exactly.
- Third-party scripts vary between runs, so compare trends rather than individual numbers.
Frequently asked questions
- Is page speed a ranking factor?
- Core Web Vitals are part of Google's page experience signals. They rarely outrank relevance, but they break ties and directly affect conversion.
- Why does my score change between runs?
- Network variance, CDN cache state and third-party scripts all move the numbers. Run the test several times and use the median.
Category: Performance · Last updated 2026-08-08