speedlify2

Lighthouse lab metrics, Axe, and Chrome UX Report field data for a list of sites recorded and compared over time. Follow us on Mastodon or Bluesky.

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moderncss.dev

https://moderncss.dev/

99PERF 100A11Y 77BEST 100SEO ✓AXE ✓CWV

Ranks Overall #507 Built Awesome #387

Data from Oct 4, 2026, 11:00 AM UTC old Measured once a week · 7 runs since Aug 21, 2026

Elsewhere: PageSpeed Insights · Calibre · Treo · CrUX Vis · Tame the Bots · Scoring Calculator · Wayback Machine

Lab data is measured using Lighthouse, Mobile mode unless otherwise specified. Field data is reported from Chrome UX Report (using p75 measurements).

Stack

Eleventy Built with Eleventy
Netlify Hosted by Netlify

Lighthouse Scores LAB Simulated

99
Performance
no change
100
Accessibility
no change
77
Best Practices
↓ -23 (-23%)
100
SEO
no change

Metrics LAB FIELD

Core Web Vitals: passing 2 of 3 assessed from real Chrome users.

Field figures are the p75 across real Chrome users over a 28-day trailing window (2026-09-05 → 2026-10-02), origin-level.

Metric Lab Simulated Field
Value Change / range Trend p75 Distribution
LCP CWV Largest Contentful Paint 1.95 s good ↓ -49 ms (-2.4%) 1.95 s – 2.00 s 1.39 s good 91.5% 4.3% 4.2%
INP CWV Interaction to Next Paint — field only, no lab run can measure it n/a — — —
CLS CWV Cumulative Layout Shift 0 good → no change 0 – 0 0 good 96.5% 2.2% 1.4%
TBT Total Blocking Time 0 ms good → no change 0 ms – 0 ms n/a —
FCP First Contentful Paint 784 ms good ↓ -169 ms (-17.7%) 784 ms – 1.64 s 1.38 s good 85.7% 9.4% 4.9%
Speed Index 784 ms good ↓ -169 ms (-17.7%) 784 ms – 1.64 s n/a —
TTFB Time to First Byte 604 ms good ↓ -49 ms (-7.5%) significant 603 ms – 653 ms 825 ms needs work 74.8% 18.1% 7.1%

LCP Subparts LAB Unthrottled

The subparts attribute LCP to your server, resource discovery, download, or rendering. Note that the Lab LCP shown above is a simulated throttled estimate.

element render delay 48 ms
time to first byte 6 ms

LCP LAB Simulated vs LCP FIELD

Lab 1.95 s
Field p75 1.39 s

The lab LCP is 1.41× the field p75 — real users likely have above-average hardware or network connectivity.

Page weight

Metric Value Change / range Trend
Page Weight 140 kB ↑ +11.8 kB (+9.5%) significant 128 kB – 188 kB
Requests 14 ↑ +1 (+7.7%) significant 13 – 14
Third-party Weight 28.8 kB ↑ +12.0 kB (+74.6%) significant 16.5 kB – 76.5 kB
Third-party CPU 5 ms ↓ -1 ms (-20%) 5 ms – 10 ms
Unused JS 0 B → no change 0 B – 0 B
Unused CSS 0 B → no change 0 B – 0 B

By resource type

Type Transfer Share Size Requests
font 51.8% 72.5 kB 3
other 15.9% 22.3 kB 4
image 12.7% 17.8 kB 3
script 9.3% 13.0 kB 2
document 6.5% 9.1 kB 1
stylesheet 3.9% 5.4 kB 1
Total 140 kB 14

Third parties 3 entities

Entity Transfer Size Main thread Simulated
Carbon Ads imagescript 26.1 kB 3 ms
Plausible 2.7 kB 2 ms
Google/Doubleclick Ads 69 B 0 ms
Total 28.8 kB 5 ms

Page health

Metric Value Change / range Trend
Main Thread Work 204 ms ↓ -65 ms (-24%) 204 ms – 354 ms
Long Tasks 0 → no change 0 – 1
DOM Elements 303 ↑ +2 (+0.7%) 301 – 303
Axe Violations Violating nodes from a full Axe CLI run (more than Lighthouse reports) 0 → no change 0 – 0
A11y Failures 0 → no change 0 – 0
A11y Failing Nodes 0 → no change 0 – 0

Main thread work

Task Time Share Duration Simulated
other 37% 76 ms
style layout 33% 67 ms
script evaluation 15% 30 ms
paint composite render 7% 14 ms
parse HTML 6% 12 ms
script parse compile 3% 6 ms
Total 204 ms

Axe violations axe-core 4.13.0, full rule set

0 violating nodes across 0 rules, 475 passing. This is a standalone Axe CLI run and is stricter than the subset Lighthouse already includes.

Best Practices failures 2 of 19 audits

  • third-party-cookies — Uses third-party cookies 2 items
  • inspector-issues — Issues were logged in the `Issues` panel in Chrome Devtools 1 item

Hygiene

HTTPS HSTS CSP Clickjacking protection Origin isolation Trusted Types bfcache h2

Measurement log

Field history 25 weeks

Weekly p75 from the CrUX History API, backfilled in a single request.

Week ending LCPINPCLSFCPTTFB
2026-09-26 1.45 s — 0 1.45 s 874 ms
2026-09-19 1.42 s — 0 1.38 s 825 ms
2026-09-12 1.42 s — 0 1.35 s 713 ms
2026-09-05 1.42 s — 0 1.35 s 666 ms
2026-08-29 1.42 s — 0 1.35 s 674 ms
2026-08-22 1.37 s — 0 1.35 s 677 ms
2026-08-15 1.34 s — 0 1.34 s 724 ms
2026-08-08 1.28 s — 0 1.27 s 754 ms
2026-08-01 1.27 s — 0 1.27 s 852 ms
2026-07-25 1.47 s — 0 1.46 s 1.03 s
2026-07-18 1.65 s — 0 1.65 s 1.06 s
2026-07-11 1.50 s — 0 1.53 s 1.06 s

Runs

Every stored run for this URL, newest first.

When Scores PerfLCPCLSTBTWeight RunsSpreadBenchTook Archive
Oct 4, 2026, 11:00 AM UTC 99 1.95 s 0 0 ms 140 kB 3/3 ±0 2,910 +17% 21.8s Wayback
Sep 27, 2026, 6:22 AM UTC 99 2.00 s 0 0 ms 128 kB 3/3 ±1 2,446 -2% 23.3s Wayback
Sep 20, 2026, 12:46 AM UTC 99 1.95 s 0 0 ms 139 kB 3/3 ±1 2,448 -2% 24.1s Wayback
Sep 12, 2026, 11:51 PM UTC 99 1.98 s 0 0 ms 139 kB 3/3 ±2 2,477 0% 24.4s Wayback
Sep 5, 2026, 8:08 PM UTC 99 1.97 s 0 0 ms 139 kB 3/3 ±5 3,049 +23% 24.2s Wayback
Aug 29, 2026, 7:47 PM UTC 99 1.96 s 0 0 ms 138 kB 3/3 ±4 2,267 -9% 24.6s Wayback
Aug 21, 2026, 5:31 AM UTC 99 1.95 s 0 0 ms 188 kB 3/3 ±6 2,475 0% 28.5s Wayback

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Use this web component to show moderncss.dev's scores on any website, updated whenever this instance re-measures. Don’t forget to bundle the speedlify2-score.js component code into your site! 

<speedlify2-score speedlify-url="https://www.speedlify.dev/" url="https://moderncss.dev/"></speedlify2-score>