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.

Charts Compare Measurement runs Embed a score Open to Work

pkg.go.dev

https://pkg.go.dev/

99PERF 88A11Y 100BEST 92SEO ✗AXE ✓CWV

Ranks Overall #1,336 Developer Tooling #46 Package Managers #9

Data from Oct 9, 2026, 10:12 AM UTC old Measured every 2 days · 21 runs since Aug 25, 2026

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

The measuring machine was faster than most in this project.

Lighthouse benchmark index was 4,032, 62% faster than this project's median of 2,487. CPU-bound metrics — TBT, TTI, main thread work — are affected by this and may have moved without the site changing at all.

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

Stack

Google Frontend Hosted by Google Frontend

Filmstrip LAB Throttled

How the page drew during the measured load, at 8 points across 5.41 s. Compare this filmstrip against another site.

  1. 677 ms
  2. 1.35 s
  3. 1.86 s
  4. 2.71 s
  5. 3.38 s
  6. 4.06 s
  7. 4.74 s
  8. 5.41 s

Lighthouse Scores LAB Simulated

99
Performance
↑ +7 (+7.6%)
88
Accessibility
no change
100
Best Practices
no change
92
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 (2026-09-10 → 2026-10-07), url-level.

Metric Lab Simulated Field
Value Change / range Trend p75 Distribution
LCP CWV Largest Contentful Paint 1.78 s good ↓ -935 ms (-34.4%) 1.25 s – 3.56 s 1.29 s good 94.6% 3.9% 1.5%
INP CWV Interaction to Next Paint — field only, no lab run can measure it n/a — 118 ms good 86.6% 11.7% 1.7%
CLS CWV Cumulative Layout Shift 0.011 good ↑ +0.006 (+120%) significant 0.005 – 0.011 0 good 99.6% 0.4% 0%
TBT Total Blocking Time 79 ms good ↓ -97 ms (-55.1%) significant 79 ms – 189 ms n/a —
FCP First Contentful Paint 1.33 s good ↓ -627 ms (-32%) significant 1.25 s – 2.09 s 1.16 s good 93.5% 4.2% 2.3%
Speed Index 1.34 s good ↓ -621 ms (-31.7%) significant 1.25 s – 2.09 s n/a —
TTFB Time to First Byte 659 ms good ↓ -19 ms (-2.8%) 644 ms – 688 ms 579 ms good 87.7% 9.7% 2.6%

LCP Subparts LAB Throttled

The subparts attribute LCP to your server, resource discovery, download, or rendering. They come from one throttled load, the same one as the filmstrip, so they add up to that load’s LCP rather than the simulated Lab LCP above.

resource load duration 1.18 s
time to first byte 619 ms
resource load delay 67 ms
element render delay 11 ms

LCP LAB Simulated vs LCP FIELD

Lab 1.78 s
Field p75 1.29 s

The lab LCP is 1.39× the field p75 — real users likely have above-average hardware or network connectivity.

Page weight

Metric Value Change / range Trend
Page Weight 565 kB ↑ +3.7 kB (+0.7%) 545 kB – 565 kB
Requests 39 ↑ +5 (+14.7%) significant 34 – 39
Third-party Weight 364 kB ↑ +3.6 kB (+1%) 343 kB – 364 kB
Third-party CPU 72 ms ↓ -15 ms (-17.1%) significant 72 ms – 117 ms
Unused JS 166 kB ↓ -1.4 kB (-0.9%) 162 kB – 168 kB
Unused CSS 21.7 kB → no change 21.7 kB – 21.7 kB

By resource type

Type Transfer Share Size Requests
script 73.6% 412 kB 5
image 13.7% 76.8 kB 29
stylesheet 6.5% 36.4 kB 2
document 6.1% 34.2 kB 1
other <0.1% 21 B 1
Total 565 kB 39

Third parties 3 entities

Entity Transfer Size Main thread Simulated
Google Tag Manager script 343 kB 64 ms
Google Analytics 20.9 kB 8 ms
Other Google APIs/SDKs 21 B 0 ms
Total 364 kB 72 ms

Without JavaScript

The same load, photographed twice at 412×823: once with scripts disabled, once as rendered.

Scripts disabled
As rendered

6.5% of pixels differ — they are nearly identical. A shifted layout counts as difference, so a <noscript> banner alone can account for a large figure.

Page health

Metric Value Change / range Trend
Main Thread Work 846 ms ↓ -174 ms (-17.1%) significant 782 ms – 1.08 s
Long Tasks 2 ↓ -3 (-60%) significant 2 – 5
DOM Elements 383 → no change 383 – 383
Axe Violations Violating nodes from a full Axe CLI run (more than Lighthouse reports) 16 → no change 16 – 16
A11y Failures 4 → no change 4 – 4
A11y Failing Nodes 16 → no change 16 – 16

Main thread work

Task Time Share Duration Simulated
script evaluation 40% 338 ms
other 37% 313 ms
style layout 13% 109 ms
script parse compile 4% 30 ms
paint composite render 3% 30 ms
parse HTML 2% 14 ms
garbage collection 2% 13 ms
Total 846 ms

Axe violations axe-core 4.13.0, full rule set

16 violating nodes across 5 rules, 580 passing. This is a standalone Axe CLI run and is stricter than the subset Lighthouse already includes.

  • critical image-alt — Images must have alternative text 6 nodes
    Offending elements (5 of 6)
    1. .go-NavigationDrawer-listItem:nth-child(6) > .go-Header-socialIcons > .go-Header-socialIcon:nth-child(1) > img 
      <img src="/static/shared/logo/social/google-groups.svg">
    2. .go-NavigationDrawer-listItem:nth-child(6) > .go-Header-socialIcons > .go-Header-socialIcon[href$="golang"]:nth-child(2) > img 
      <img src="/static/shared/logo/social/github.svg">
    3. .go-NavigationDrawer-listItem:nth-child(6) > .go-Header-socialIcons > .go-Header-socialIcon[href$="golang"]:nth-child(3) > img 
      <img src="/static/shared/logo/social/twitter.svg">
    4. .go-NavigationDrawer-listItem:nth-child(6) > .go-Header-socialIcons > .go-Header-socialIcon:nth-child(4) > img 
      <img src="/static/shared/logo/social/reddit.svg">
    5. .go-NavigationDrawer-listItem:nth-child(6) > .go-Header-socialIcons > .go-Header-socialIcon:nth-child(5) > img 
      <img src="/static/shared/logo/social/slack.svg">
  • serious link-name — Links must have discernible text 6 nodes
    Offending elements (5 of 6)
    1. .go-NavigationDrawer-listItem:nth-child(6) > .go-Header-socialIcons > .go-Header-socialIcon:nth-child(1) 
      <a class="go-Header-socialIcon" href="https://groups.google.com/g/golang-nuts" tabindex="-1"><img src="/static/shared/logo/social/google-groups.svg"></a>
    2. .go-NavigationDrawer-listItem:nth-child(6) > .go-Header-socialIcons > .go-Header-socialIcon[href$="golang"]:nth-child(2) 
      <a class="go-Header-socialIcon" href="https://github.com/golang" tabindex="-1"><img src="/static/shared/logo/social/github.svg"></a>
    3. .go-NavigationDrawer-listItem:nth-child(6) > .go-Header-socialIcons > .go-Header-socialIcon[href$="golang"]:nth-child(3) 
      <a class="go-Header-socialIcon" href="https://twitter.com/golang" tabindex="-1"><img src="/static/shared/logo/social/twitter.svg"></a>
    4. .go-NavigationDrawer-listItem:nth-child(6) > .go-Header-socialIcons > .go-Header-socialIcon:nth-child(4) 
      <a class="go-Header-socialIcon" href="https://www.reddit.com/r/golang/" tabindex="-1"><img src="/static/shared/logo/social/reddit.svg"></a>
    5. .go-NavigationDrawer-listItem:nth-child(6) > .go-Header-socialIcons > .go-Header-socialIcon:nth-child(5) 
      <a class="go-Header-socialIcon" href="https://invite.slack.golangbridge.org/" tabindex="-1"><img src="/static/shared/logo/social/slack.svg"></a>
  • minor aria-allowed-role — ARIA role should be appropriate for the element 2 nodes
    Offending elements
    1. .js-headerLogo 
      <a href="https://go.dev/" class="js-headerLogo" data-gtmc="nav link" data-test-id="go-header-logo-link" role="heading" aria-level="1"> <img class="go-Header-logo" src="/static/shared/logo/go-white.sv…
    2. #AutoComplete 
      <input class="go-Input js-searchFo..." data-test-id="homepage-search" id="AutoComplete" role="textbox" aria-label="Search packages or s..." aria-describedby="SearchTipContent" type="search" name="q" …
  • moderate landmark-unique — Landmarks should have a unique role or role/label/title (i.e. accessible name) combination 1 node
    Offending element
    1. .go-Header-nav 
      <nav class="go-Header-nav">
  • moderate region — All page content should be contained by landmarks 1 node
    Offending element
    1. .Cookie-notice > div:nth-child(1) 
      <div>go.dev uses cookies from Google to deliver and enhance the quality of its services and to analyze traffic. <a target="_blank" href="https://policies.google.com/technologies/cookies">Learn more.<…

Accessibility failures 4 of 31 audits

  • image-alt — Image elements do not have `[alt]` attributes 6 nodes
  • link-name — Links do not have a discernible name 6 nodes
  • target-size — Touch targets do not have sufficient size or spacing. 3 nodes
  • label-content-name-mismatch — Elements with visible text labels do not have matching accessible names. 1 node

SEO failures 1 of 9 audits

  • image-alt — Image elements do not have `[alt]` attributes 6 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
2026-10-03 1.32 s 118 ms 0 1.19 s 601 ms
2026-09-26 1.33 s 118 ms 0 1.20 s 582 ms
2026-09-19 1.32 s 118 ms 0 1.20 s 589 ms
2026-09-12 1.34 s 119 ms 0 1.19 s 629 ms
2026-09-05 1.28 s 122 ms 0 1.15 s 585 ms
2026-08-29 1.30 s 119 ms 0 1.16 s 597 ms
2026-08-22 1.34 s 118 ms 0 1.17 s 627 ms
2026-08-15 1.32 s 116 ms 0 1.19 s 597 ms
2026-08-08 1.34 s 108 ms 0 1.20 s 605 ms
2026-08-01 1.29 s 106 ms 0 1.16 s 586 ms
2026-07-25 1.24 s 106 ms 0 1.14 s 558 ms
2026-07-18 1.23 s 105 ms 0 1.10 s 565 ms

Runs

Every stored run for this URL, newest first.

When Scores PerfLCPCLSTBTWeight RunsSpreadBenchTook Archive
Oct 9, 2026, 10:12 AM UTC 99 1.78 s 0.011 79 ms 565 kB 3/3 ±1 4,032 +62% 50.9s Wayback
Oct 7, 2026, 2:43 AM UTC 92 2.72 s 0.005 176 ms 561 kB 3/3 ±9 2,442 -2% 62.1s Wayback
Oct 4, 2026, 7:22 PM UTC 97 1.26 s 0.005 189 ms 561 kB 3/3 ±5 2,502 +1% 55.6s Wayback
Oct 1, 2026, 12:23 AM UTC 98 1.25 s 0.005 167 ms 561 kB 3/3 ±1 2,435 -2% 55.5s Wayback
Sep 28, 2026, 11:59 PM UTC 92 2.86 s 0.005 166 ms 559 kB 3/3 ±5 2,459 -1% 56.5s Wayback
Sep 25, 2026, 4:46 PM UTC 97 1.70 s 0.011 164 ms 561 kB 3/3 ±1 2,514 +1% 55.9s Wayback
Sep 23, 2026, 6:04 AM UTC 92 2.93 s 0.006 160 ms 553 kB 3/3 ±6 2,502 +1% 56.6s Wayback
Sep 21, 2026, 1:35 AM UTC 98 1.25 s 0.006 171 ms 555 kB 3/3 ±7 2,480 0% 56.4s Wayback
Sep 18, 2026, 5:33 PM UTC 99 1.78 s 0.005 96 ms 557 kB 3/3 ±2 2,955 +19% 53.6s Wayback
Sep 16, 2026, 9:14 AM UTC 98 1.25 s 0.005 165 ms 552 kB 3/3 ±1 2,468 -1% 57.2s Wayback
Sep 14, 2026, 5:54 AM UTC 99 1.26 s 0.005 116 ms 555 kB 3/3 ±5 3,185 +28% 53.8s Wayback
Sep 11, 2026, 11:25 PM UTC 98 1.26 s 0.006 145 ms 552 kB 3/3 ±0 2,310 -7% 56.5s Wayback
Sep 9, 2026, 8:30 PM UTC 98 1.78 s 0.005 143 ms 551 kB 3/3 ±0 2,300 -8% 28.2s Wayback
Sep 7, 2026, 7:03 PM UTC 99 1.25 s 0.006 135 ms 551 kB 3/3 ±1 2,339 -6% 27.3s Wayback
Sep 5, 2026, 12:47 PM UTC 98 1.69 s 0.006 159 ms 551 kB 3/3 ±5 2,484 0% 29.3s Wayback
Sep 4, 2026, 10:50 AM UTC 98 1.28 s 0.006 146 ms 548 kB 3/3 ±1 2,447 -2% 27.6s Wayback
Sep 3, 2026, 1:09 AM UTC 99 1.55 s 0.005 90 ms 549 kB 3/3 ±1 3,021 +21% 25.4s Wayback
Sep 1, 2026, 11:08 PM UTC 94 2.71 s 0.006 126 ms 549 kB 3/3 ±6 2,640 +6% 27.8s Wayback
Aug 31, 2026, 9:26 PM UTC 87 3.56 s 0.006 148 ms 548 kB 3/3 ±21 2,488 0% 29s Wayback
Aug 26, 2026, 7:03 PM UTC 98 1.29 s 0.006 138 ms 545 kB 3/3 ±34 2,439 -2% 28.6s Wayback
Aug 25, 2026, 4:36 PM UTC 94 2.88 s 0.011 147 ms 545 kB 3/3 ±3 2,436 -2% 28s Wayback