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 ·

londoncss.dev

https://www.londoncss.dev/

60 100 96 90 –CWV 35AXE

Data from Aug 21, 2026, 1:47 PM UTC — 5h old.

Built Awesome · 1 measurement · since Aug 21, 2026 · last attempt 5h

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.

ES Hosted by ESF

Scores

60
Performance
no change
100
Accessibility
no change
96
Best Practices
no change
90
SEO
no change

Lab metrics Lighthouse, mobile

Metric Current Previous Change Best Worst Trend
LCP Largest Contentful Paint 7.24 s — — 7.24 s 7.24 s
CLS Cumulative Layout Shift 0.001 — — 0.001 0.001
TBT Total Blocking Time 222 ms — — 222 ms 222 ms
FCP First Contentful Paint 4.99 s — — 4.99 s 4.99 s
Speed Index 4.99 s — — 4.99 s 4.99 s
TTFB Time to First Byte 698 ms — — 698 ms 698 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 1.18 s
time to first byte 177 ms

Page weight

Metric Current Previous Change Best Worst Trend
Page Weight 881.7 kB — — 881.7 kB 881.7 kB
Requests 25 — — 25 25
Third-party Weight 839.8 kB — — 839.8 kB 839.8 kB
Third-party CPU 131 ms — — 131 ms 131 ms
Unused JS 284.3 kB — — 284.3 kB 284.3 kB
Unused CSS 203.3 kB — — 203.3 kB 203.3 kB

By resource type

script 533.7 kB · 10 req
stylesheet 212.1 kB · 4 req
font 93.6 kB · 3 req
document 41.5 kB · 1 req
other 723 B · 7 req
third party 839.8 kB · 22 req

Third parties 3 entities

839.8 kB transferred, 131 ms of main thread time. This is the number most likely to regress without anyone on your team shipping anything.

Google CDN 623.4 kB · 107 ms CPU
Other Google APIs/SDKs 116.7 kB · 24 ms CPU
Google Fonts 99.8 kB · 0 ms CPU

Page health

Metric Current Previous Change Best Worst Trend
Main Thread Work 1.48 s — — 1.48 s 1.48 s
Long Tasks 7 — — 7 7
DOM Elements 649 — — 649 649
Axe Violations Violating nodes from a full axe run — stricter than Lighthouse's subset 35 — — 35 35
A11y Failures 0 — — 0 0
A11y Failing Nodes 0 — — 0 0

Main thread work

script evaluation 653 ms
other 405 ms
script parse compile 157 ms
style layout 155 ms
parse HTML 73 ms
paint composite render 39 ms

Axe violations axe-core 4.13.0, full rule set

35 violating nodes across 5 rules, 659 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 region — All page content should be contained by landmarks 30 nodes
  • moderate landmark-unique — Landmarks should have a unique role or role/label/title (i.e. accessible name) combination 2 nodes
  • critical aria-allowed-attr — Elements must only use supported ARIA attributes 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

Hygiene

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

HTTPS HSTS CSP Clickjacking protection Origin isolation Trusted Types bfcache h2 4 console errors

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, 1:47 PM UTC 60 7.24 s 0.001 222 ms 881.7 kB 3/3 ±6 2,482 29s

Embed this score

Live below, then the markup that produces it. Drop that on any page to show londoncss.dev'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://www.londoncss.dev/"></speedlify-score>