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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atom-editor.cc

https://atom-editor.cc/

99PERF 90A11Y 100BEST 82SEO ✗AXE ✓CWV

Ranks Overall #1,388 Built Awesome #941

Data from Oct 2, 2026, 11:04 PM UTC old Measured once a week · 7 runs since Aug 20, 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
Cloudflare Hosted by Cloudflare

Lighthouse Scores LAB Simulated

99
Performance
no change
90
Accessibility
no change
100
Best Practices
no change
82
SEO
no change

Metrics LAB FIELD

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

Field figures are the p75 across real Chrome users over a 28-day trailing window (2026-09-02 → 2026-09-29), url-level.

Metric Lab Simulated Field
Value Change / range Trend p75 Distribution
LCP CWV Largest Contentful Paint 1.83 s good ↓ -9 ms (-0.5%) 1.60 s – 2.02 s 1.87 s good 87% 7% 5.9%
INP CWV Interaction to Next Paint — field only, no lab run can measure it n/a — 88 ms good 96.9% 2.5% 0.6%
CLS CWV Cumulative Layout Shift 0 good → no change 0 – 0 0 good 95.7% 0.6% 3.7%
TBT Total Blocking Time 0 ms good → no change 0 ms – 0 ms n/a —
FCP First Contentful Paint 1.53 s good ↓ -11 ms (-0.7%) 869 ms – 1.58 s 1.52 s good 81.5% 11.8% 6.7%
Speed Index 1.53 s good ↓ -11 ms (-0.7%) 869 ms – 1.58 s n/a —
TTFB Time to First Byte 616 ms good ↓ -6 ms (-1%) 469 ms – 666 ms 966 ms needs work 68.2% 22.8% 8.9%

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 80 ms
resource load delay 44 ms
resource load duration 26 ms
time to first byte 10 ms

LCP LAB Simulated vs LCP FIELD

Lab 1.83 s
Field p75 1.87 s

The lab LCP is 0.98× the field p75 — real users likely have similar hardware or network connectivity to the lab test.

Page weight

Metric Value Change / range Trend
Page Weight 277 kB ↓ -101 B 276 kB – 278 kB
Requests 24 → no change 24 – 24
Third-party Weight 10.2 kB → no change 9.6 kB – 11.5 kB
Third-party CPU 4 ms ↓ -1 ms (-15.6%) 3 ms – 5 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
image 88% 239 kB 18
font 6.7% 18.1 kB 1
script 3.8% 10.2 kB 1
document 1.4% 3.8 kB 1
other 0.2% 494 B 1
Total 277 kB 24

Third parties 1 entities

Entity Transfer Size Main thread Simulated
Cloudflare script 10.2 kB 4 ms
Total 10.2 kB 4 ms

Page health

Metric Value Change / range Trend
Main Thread Work 505 ms ↑ +15 ms (+3%) 369 ms – 505 ms
Long Tasks 1 → no change 0 – 1
DOM Elements 180 → no change 180 – 180
Axe Violations Violating nodes from a full Axe CLI run (more than Lighthouse reports) 13 → no change 13 – 15
A11y Failures 3 → no change 3 – 3
A11y Failing Nodes 5 → no change 5 – 5

Main thread work

Task Time Share Duration Simulated
other 50% 252 ms
style layout 31% 159 ms
script evaluation 9% 47 ms
paint composite render 6% 29 ms
parse HTML 3% 17 ms
script parse compile 0% 1 ms
Total 505 ms

Axe violations axe-core 4.13.0, full rule set

13 violating nodes across 4 rules, 321 passing. This is a standalone Axe CLI run and is stricter than the subset Lighthouse already includes.

  • moderate region — All page content should be contained by landmarks 8 nodes
    Offending elements (5 of 8)
    1. .sunset-banner 
      <p class="sunset-banner sunset-text-color">Atom and all repositories under Atom will be archived on December 15, 2022. <a class="sunset-text-color" href="https://github.blog/2022-06-08-sunsetting-ato…
    2. .hero-download 
      <ul class="hero-header-item hero-download">
    3. .hero-meta 
      <p class="hero-meta">
    4. .hero-features 
      <div class="hero-features"> <h1 class="hero-tagline">A hackable <span class="hero-tagline-highlight">text editor</span> for the 21st Century</h1> </div>
    5. #teletype 
      <section class="section section--realtime" id="teletype">
  • critical image-alt — Images must have alternative text 3 nodes
    Offending elements
    1. .logo-wordmark 
      <img src="/assets/images/index-atom-wordmark.svg" class="logo-wordmark">
    2. #teletype > .wrapper > .welcome-bgs > .welcome-bg.welcome-bg--screenshot 
      <img src="/assets/images/index-teletype-screenshot.png" class="welcome-bg welcome-bg--screenshot">
    3. #github > .wrapper > .welcome-bgs > .welcome-bg.welcome-bg--screenshot 
      <img src="/assets/images/index-github-screenshot.png" class="welcome-bg welcome-bg--screenshot">
  • moderate heading-order — Heading levels should only increase by one 1 node
    Offending element
    1. #teletype > .wrapper > h3 
      <h3>Teletype for Atom</h3>
  • moderate landmark-one-main — Document should have one main landmark 1 node
    Offending element
    1. html 
      <html lang="en" prefix="og: http://ogp.me/ns#">

Accessibility failures 3 of 23 audits

  • image-alt — Image elements do not have `[alt]` attributes 3 nodes
  • heading-order — Heading elements are not in a sequentially-descending order 1 node
  • landmark-one-main — Document does not have a main landmark. 1 node

SEO failures 2 of 8 audits

  • link-text — Links do not have descriptive text 2 items
  • image-alt — Image elements do not have `[alt]` attributes 3 items

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 1.78 s 87 ms 0 1.42 s 890 ms
2026-09-19 1.72 s 87 ms 0 1.37 s 875 ms
2026-09-12 1.74 s 91 ms 0 1.37 s 852 ms
2026-09-05 1.73 s 88 ms 0 1.35 s 875 ms
2026-08-29 1.81 s 93 ms 0 1.48 s 964 ms
2026-08-22 1.81 s 93 ms 0 1.48 s 995 ms
2026-08-15 1.81 s 91 ms 0 1.50 s 978 ms
2026-08-08 1.81 s 93 ms 0 1.50 s 960 ms
2026-08-01 1.75 s 99 ms 0 1.43 s 941 ms
2026-07-25 1.80 s 99 ms 0 1.48 s 942 ms
2026-07-18 1.84 s 102 ms 0 1.48 s 971 ms
2026-07-11 1.85 s 105 ms 0 1.50 s 945 ms

Runs

Every stored run for this URL, newest first.

When Scores PerfLCPCLSTBTWeight RunsSpreadBenchTook Archive
Oct 2, 2026, 11:04 PM UTC 99 1.83 s 0 0 ms 277 kB 3/3 ±0 2,479 0% 22.8s Wayback
Sep 25, 2026, 12:33 AM UTC 99 1.84 s 0 0 ms 277 kB 3/3 ±1 2,421 -3% 23s Wayback
Sep 17, 2026, 11:29 PM UTC 100 1.60 s 0 0 ms 277 kB 3/3 ±1 2,342 -6% 23s Wayback
Sep 10, 2026, 9:32 PM UTC 99 1.83 s 0 0 ms 277 kB 3/3 ±1 3,232 +30% 22.1s Wayback
Sep 3, 2026, 7:22 PM UTC 99 2.02 s 0 0 ms 276 kB 3/3 ±0 3,042 +22% 21.4s Wayback
Aug 27, 2026, 7:06 PM UTC 99 1.88 s 0 0 ms 278 kB 3/3 ±1 2,373 -5% 22.7s Wayback
Aug 20, 2026, 4:30 PM UTC 99 1.92 s 0 0 ms 278 kB 3/3 ±0 2,452 -1% 22.8s Wayback

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