Free Website Speed Test

What does a website speed test measure?

A useful website speed test looks beyond one loading-time number. WebMetrica runs a controlled browser scan and evaluates performance signals including rendering speed, layout stability, server response, page weight, network requests and render-blocking resources when those measurements are available.

Core Web Vitals and lab performance signals

Core Web Vitals focus on loading, responsiveness and visual stability. In field data, the primary metrics are Largest Contentful Paint (LCP), Interaction to Next Paint (INP) and Cumulative Layout Shift (CLS). A controlled lab test cannot reproduce real user interaction history, so WebMetrica clearly separates measured lab signals from field-data claims.

Largest Contentful Paint (LCP)

LCP measures when the largest visible content element finishes rendering. Slow images, fonts, server response and render-blocking resources can all delay it.

Cumulative Layout Shift (CLS)

CLS captures unexpected movement of visible content. Missing image dimensions, late-loading banners and injected interface elements are common causes.

Responsiveness: INP vs TBT

INP is a field metric based on real user interactions. WebMetrica's browser lab test can use Total Blocking Time (TBT) as a controlled diagnostic signal, but it does not label TBT as measured INP.

What is a good website speed?

There is no single perfect loading-time number for every page. For Core Web Vitals, commonly used “good” thresholds are LCP at 2.5 seconds or faster, INP at 200 milliseconds or faster, and CLS at 0.1 or lower. WebMetrica also looks at the underlying technical causes so the score leads to an actionable fix rather than a vanity number.

Why is my website slow?

• Large or poorly optimized images and video.
• Slow server response or excessive backend processing.
• Render-blocking JavaScript and CSS.
• Too many third-party scripts, tags or widgets.
• Large JavaScript bundles that block the browser main thread.
• Too many network requests or long redirect chains.
• Inefficient caching, compression or content delivery.
• Web fonts and above-the-fold assets loading too late.

How to improve website speed

1. Fix the biggest measurable bottleneck first. Improving the dominant constraint usually produces more value than making dozens of tiny changes.
2. Optimize the critical rendering path. Prioritize the resources needed for above-the-fold content and defer nonessential work.
3. Reduce transferred bytes. Compress and resize images, remove unused code and avoid shipping assets the page does not need.
4. Reduce browser work. Limit long JavaScript tasks and unnecessary third-party scripts.
5. Improve delivery. Use effective caching, compression, modern protocols and a suitable CDN when appropriate.
6. Retest after every meaningful change. Performance work should be measured, not guessed.

Website speed test FAQ