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Site Speed Tester

Run any page through Google PageSpeed Insights. Get the Lighthouse performance score, Core Web Vitals (LCP, CLS, INP), and the top opportunities to improve speed.

// your details

Powered by Google PageSpeed Insights. Free; can take 30–90 seconds for larger sites.

// the metrics that matter

Core Web Vitals decoded.

Google uses Core Web Vitals as a ranking signal and a UX benchmark. Each metric measures a different aspect of page experience — perception of speed, visual stability, and interactivity. Pass all three at the 75th percentile of your real traffic and the page is considered to deliver a good experience.

LCP≤ 2.5s

Largest Contentful Paint

How quickly the largest visible element renders. Slow LCP = perception of slow site.

CLS≤ 0.1

Cumulative Layout Shift

Visual stability. Measures how much elements move around after load. Hurts trust.

INP≤ 200ms

Interaction to Next Paint

Responsiveness to user input. Replaced FID in 2024 as the Core Web Vital.

// reading the score

What the Lighthouse number means.

The performance score is a 0–100 blend of lab metrics. It falls into three bands — and where you land tells you how urgent the work is.

90–100

Good

Fast for most users. Maintain it — regressions creep in with every new script and image.

50–89

Needs work

Noticeably slow on mid-tier mobile. There's measurable ranking and conversion upside in fixing it.

0–49

Poor

Painful on real devices. Likely losing users before the page is usable. Prioritize the opportunities.

// how the test works

Lab data vs. field data.

We run your URL through Google PageSpeed Insights, which returns two kinds of data. Knowing which is which is the difference between debugging confidently and chasing noise.

LAB

Lighthouse, one controlled load

A single simulated page load on a throttled connection and emulated mobile device. Repeatable and diagnostic — it tells you why a page is slow and pinpoints what to fix. It can vary run-to-run, so read the trend, not one number.

FIELD

CrUX, real Chrome users

Chrome User Experience Report data aggregated from real visitors over the prior 28 days. This is what Google actually ranks on when it's available. If a URL has too little traffic, field data may be absent — that's when lab data carries the weight.

// common opportunities

The fixes that move the needle.

Most performance reports surface the same handful of issues. Here's what they mean and which metric each one tends to improve.

Oversized images

Serve next-gen formats (WebP/AVIF), size images to their rendered dimensions, and lazy-load below the fold.

improves LCP

Render-blocking resources

Defer non-critical JS and inline critical CSS so the browser can paint without waiting on the network.

improves LCP / FCP

Unused JavaScript

Code-split and tree-shake bundles. Shipping JS the page never runs just delays interactivity.

improves INP / TBT

No explicit dimensions

Set width/height (or aspect-ratio) on images and embeds so nothing jumps as the page loads.

improves CLS

Slow server response

Cut TTFB with caching, a CDN, and a faster backend. Everything downstream waits on the first byte.

improves LCP / TTFB

Heavy third-party scripts

Audit tag managers, chat widgets, and trackers. Each one competes for the main thread.

improves INP
// faq

Speed questions, answered.

What are Core Web Vitals?
Core Web Vitals are three metrics Google uses to measure real-world page experience: Largest Contentful Paint (LCP) for loading speed, Cumulative Layout Shift (CLS) for visual stability, and Interaction to Next Paint (INP) for responsiveness. INP replaced First Input Delay (FID) as a Core Web Vital in March 2024. They're part of Google's ranking systems and a direct read on how fast your page feels.
What's a good Lighthouse performance score?
Lighthouse scores 0–100. 90 and above is 'good' (green), 50–89 is 'needs improvement' (orange), and 0–49 is 'poor' (red). The score is a weighted blend of lab metrics — it's a useful directional benchmark, but field data (how real users experience the page) is what ultimately feeds Google's ranking signals.
What's the difference between lab data and field data?
Lab data comes from a single simulated load in a controlled environment (what Lighthouse runs) — repeatable and great for debugging. Field data, or CrUX (Chrome User Experience Report), is aggregated from real Chrome users over the prior 28 days. Google ranks on field data when it's available; lab data tells you why and how to fix it.
Does page speed actually affect rankings?
Yes, but it's a tiebreaker, not a magic lever. Core Web Vitals are a confirmed ranking factor, so when two pages are otherwise comparable, the faster one has an edge. The bigger win is usually conversion: faster pages bounce less and convert more, which compounds the SEO benefit.
Why do my scores change every time I run the test?
Lab scores vary run-to-run because they depend on network conditions, server load, and which third-party scripts respond quickly that moment. Small fluctuations are normal — look at the trend across several runs rather than a single number, and weight the field (CrUX) data when it's present.
What's the single highest-impact speed fix for most sites?
For most pages it's the LCP element — usually a hero image or large above-the-fold block. Compressing and properly sizing that image, serving it in a modern format, and preloading it often moves LCP more than any other single change. After that, cutting render-blocking JavaScript is typically the next biggest lever.
Need help fixing the issues?
Our on-page SEO and technical audit cover Core Web Vitals tuning across every template.
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