speedlify2

Lighthouse lab metrics and Chrome UX Report field data for a list of sites, recorded on every run and compared over time.

Measurement runs · Embed a score · Field data from the Chrome UX Report ·

design-guide.publishing.service.gov.uk

https://design-guide.publishing.service.gov.uk/

98 100 100 100 CWV 7AXE

Data from Aug 21, 2026, 2:38 PM UTC — 4h old.

Built Awesome · 2 measurements · since Aug 20, 2026 · last attempt 4h

Stack

Detected on the same page load as the accessibility pass — the generator from <meta name="generator"> or the shape of the page, the host from response headers.

GitHub Pages Hosted by GitHub Pages

Scores

98
Performance
no change
100
Accessibility
no change
100
Best Practices
no change
100
SEO
no change

Lab metrics Lighthouse, mobile

Metric Current Previous Change Best Worst Trend
LCP Largest Contentful Paint 1.50 s 1.50 s 1.50 s
CLS Cumulative Layout Shift 0.083 0.083 0.083
TBT Total Blocking Time 0 ms 0 ms 0 ms
FCP First Contentful Paint 1.50 s 1.50 s 1.50 s
Speed Index 1.50 s 1.50 s 1.50 s
TTFB Time to First Byte 602 ms 602 ms 602 ms

What LCP is made of

A flat LCP number tells you something regressed. The subparts tell you whether it was the server, resource discovery, the download, or rendering.

element render delay 78 ms
time to first byte 6 ms

Page weight

Metric Current Previous Change Best Worst Trend
Page Weight 146.6 kB 146.6 kB 146.6 kB
Requests 9 9 9
Third-party Weight 0 B 0 B 0 B
Third-party CPU 0 ms 0 ms 0 ms
Unused JS 21.1 kB 21.1 kB 21.1 kB
Unused CSS 19.8 kB 19.8 kB 19.8 kB

By resource type

font 65.3 kB · 2 req
script 33.8 kB · 2 req
stylesheet 21.6 kB · 1 req
image 18.5 kB · 2 req
document 5.9 kB · 1 req

Page health

Metric Current Previous Change Best Worst Trend
Main Thread Work 255 ms 255 ms 255 ms
Long Tasks 0 0 0
DOM Elements 146 146 146
Axe Violations Violating nodes from a full axe run — stricter than Lighthouse's subset 7 7 7
A11y Failures 0 0 0
A11y Failing Nodes 0 0 0

Main thread work

other 120 ms
style layout 59 ms
script evaluation 51 ms
parse HTML 15 ms
paint composite render 9 ms
script parse compile 2 ms

Axe violations axe-core 4.13.0, full rule set

7 violating nodes across 6 rules, 276 passing. This is a standalone axe run, stricter than the subset Lighthouse folds into its score above — and it is the second tiebreaker in the ranking.

  • moderate landmark-unique — Landmarks should have a unique role or role/label/title (i.e. accessible name) combination 2 nodes
  • moderate landmark-banner-is-top-level — Banner landmark should not be contained in another landmark 1 node
  • moderate landmark-contentinfo-is-top-level — Contentinfo landmark should not be contained in another landmark 1 node
  • moderate landmark-no-duplicate-banner — Document should not have more than one banner landmark 1 node
  • moderate landmark-no-duplicate-contentinfo — Document should not have more than one contentinfo landmark 1 node
  • moderate region — All page content should be contained by landmarks 1 node

Hygiene

Changes rarely — which is exactly why a change is worth noticing.

HTTPS HSTS CSP Clickjacking protection Origin isolation Trusted Types bfcache h2

Measurement log

Every stored run for this URL, newest first. Failures are kept as records — "this site was down on Tuesday" is data too.

When PerfLCPCLSTBTWeight RunsSpreadBenchTook
Aug 21, 2026, 2:38 PM UTC 98 1.50 s 0.083 0 ms 146.6 kB 3/3 ±3 2,479 27.9s
Aug 20, 2026, 7:41 PM UTC TRACING_ALREADY_STARTED: An internal Chrome error occurred. Please restart Chrome and try re-running Lighthouse. 18.7s

Embed this score

Live below, then the markup that produces it. Drop that on any page to show design-guide.publishing.service.gov.uk's scores, updated whenever this instance re-measures — more about the component. Don’t forget to bundle the speedlify-score.js component code into your site!

<speedlify-score speedlify-url="https://zachleat.github.io/speedlify2/" url="https://design-guide.publishing.service.gov.uk/"></speedlify-score>