Performance checker
Find out what is slowing your website down
A slow site is usually slow for a reason you can name: too many resources, a script that blocks rendering, images shipped far larger than they are displayed, or caching that was never configured. VeriFixScan measures what your pages actually download and reports where the weight and the delay come from.
Weight is measured, not estimated
The scanner fetches the resources your pages reference and records their real transfer size — HTML, CSS, JavaScript, fonts, images and video. The report names the heaviest individual files rather than only giving a total, because a page weight figure tells you there is a problem while a list of the five biggest files tells you where it is.
Delivery matters as much as size
Compression, cache headers, CDN cache status and Time to First Byte are checked from the responses your server really returned. A well-optimised page served without compression and without caching is still slow, and that is a configuration fix rather than a rebuild.
Core Web Vitals, measured in a real browser
LCP, INP and CLS are measured in a browser rather than inferred from the markup, and they are measured on mobile as well as desktop. The image responsible for the Largest Contentful Paint is identified, which is usually the single most actionable performance finding on a content page.
How this relates to PageSpeed Insights and Lighthouse
It does not replace them, and it is not trying to. Those tools go deep on one URL at a time. VeriFixScan measures the resource inventory across the pages it crawled, so it answers a different question: not 'how fast is this page' but 'what is heavy, uncached or broken across my site'. Use both — they disagree less often than they complement each other.
What gets measured
A selection from the performance checks. Coverage under the scan budget is reported explicitly, so you know what was measured and what was not.
Time to First Byte
Server think-time isolated from DNS, TCP and TLS.
Core Web Vitals
Field metrics (LCP, INP, CLS) measured in a real browser.
Observable page weight
Total transfer weight really observed: HTML plus every measured resource.
Potentially render-blocking resources
Stylesheets and synchronous scripts declared in the head.
Heavy JavaScript files
Individual scripts whose measured transfer size is unusually large.
Unused CSS
Share of CSS rules never applied by the page.
Image payload
Weight and formats of the images referenced by the pages.
Compression
Responses are compressed (gzip, brotli or zstd).
Static resource caching
Cache-Control, ETag and Last-Modified really returned for static resources.
LCP image
The image responsible for the Largest Contentful Paint.
Mobile payload
Page payload a phone on a mobile network really has to download.
Performance measurement coverage
How much of the resource inventory could really be measured under the scan budget.
Measurements describe the pages that were crawled, at the moment they were crawled, from the network path the scanner used. They are not a substitute for real-user monitoring of your own traffic.
Enter your website address and VeriFixScan analyses it straight away. No account, no installation, nothing to add to your site.
Frequently asked questions
- Why is my website slow?
- Most often payload and delivery: heavy scripts and images, render-blocking resources in the head, missing compression or missing cache headers. The report names which of these applies to your pages.
- Do you measure Core Web Vitals?
- Yes — LCP, INP and CLS, measured in a real browser, on desktop and on mobile.
- Is this the same as a website speed test?
- Not quite. A speed test times one page load. This measures the resources across the pages that were crawled and reports which are heavy, uncached, unused or broken.
- Does it replace PageSpeed Insights?
- No. PageSpeed goes deep on a single URL; this goes wide across your site. They answer different questions and are worth using together.
- Can it tell me which image is the problem?
- Yes. The heaviest resources are listed individually, and the image responsible for the Largest Contentful Paint is identified.