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 ·

blog.mozilla.org/addons

https://blog.mozilla.org/addons

98 95 100 83 ✓CWV 5AXE

Data from Aug 20, 2026, 3:52 PM UTC — 27h old.

Built Awesome · 1 measurement · since Aug 20, 2026 · last attempt 27h

This URL redirects to https://blog.mozilla.org/addons/.

A trailing slash only, so both forms are treated as one site rather than two — one history, measured once. Lighthouse follows the redirect, so the numbers below describe the canonical page; the only cost is an extra hop on each run.

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.

Cloudflare Hosted by Cloudflare

Core Web Vitals field data, origin-level

Real Chrome users, 28-day window (2026-07-22 → 2026-08-18). This is what Google measures you on.

LCP 1.53 s good
INP 117 ms good
CLS 0 good

Scores

98
Performance
no change
95
Accessibility
no change
100
Best Practices
no change
83
SEO
no change

Lab metrics Lighthouse, mobile

Metric Current Previous Change Best Worst Trend
LCP Largest Contentful Paint 1.67 s — — 1.67 s 1.67 s
CLS Cumulative Layout Shift 0.025 — — 0.025 0.025
TBT Total Blocking Time 136 ms — — 136 ms 136 ms
FCP First Contentful Paint 1.60 s — — 1.60 s 1.60 s
Speed Index 1.60 s — — 1.60 s 1.60 s
TTFB Time to First Byte 465 ms — — 465 ms 465 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.

resource load delay 61 ms
element render delay 60 ms
time to first byte 44 ms
resource load duration 18 ms

Field data Chrome UX Report, origin-level

Real Chrome users, 28-day trailing window (2026-07-22 → 2026-08-18). This is what Google measures you on.

Metric p75 Rating Distribution (good / needs work / poor)
LCP CWV 1.53 s good 89.9% good
INP CWV Interaction to Next Paint — field only, Lighthouse cannot measure this in a lab run 117 ms good 88.5% good
CLS CWV 0 good 96% good
FCP 1.47 s good 82.3% good
TTFB 1.04 s needs-improvement 66.3% good

Lab vs field

Lab LCP 1.67 s · field p75 1.53 s · real users are 0.92× faster than the lab.

Field history 25 weeks

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

Week ending LCPINPCLSFCPTTFB
2026-08-15 1.56 s 120 ms 0 1.50 s 1.07 s
2026-08-08 1.56 s 118 ms 0 1.50 s 1.06 s
2026-08-01 1.54 s 115 ms 0 1.47 s 1.01 s
2026-07-25 1.57 s 115 ms 0 1.49 s 1.02 s
2026-07-18 1.68 s 115 ms 0 1.59 s 1.13 s
2026-07-11 1.63 s 107 ms 0 1.56 s 1.09 s
2026-07-04 1.79 s 106 ms 0 1.72 s 1.35 s
2026-06-27 1.78 s 108 ms 0 1.71 s 1.35 s
2026-06-20 1.81 s 112 ms 0 1.73 s 1.32 s
2026-06-13 1.79 s 116 ms 0 1.70 s 1.29 s
2026-06-06 1.57 s 123 ms 0 1.47 s 959 ms
2026-05-30 1.55 s 119 ms 0 1.44 s 949 ms

Page weight

Metric Current Previous Change Best Worst Trend
Page Weight 344.8 kB — — 344.8 kB 344.8 kB
Requests 22 — — 22 22
Third-party Weight 163.5 kB — — 163.5 kB 163.5 kB
Third-party CPU 52 ms — — 52 ms 52 ms
Unused JS 71.0 kB — — 71.0 kB 71.0 kB
Unused CSS 14.2 kB — — 14.2 kB 14.2 kB

By resource type

script 205.8 kB · 6 req
font 70.2 kB · 3 req
image 28.7 kB · 7 req
stylesheet 27.8 kB · 3 req
document 11.4 kB · 1 req
other 891 B · 2 req
third party 344.8 kB · 22 req

Third parties 1 entities

163.5 kB transferred, 52 ms of main thread time. This is the number most likely to regress without anyone on your team shipping anything.

Google Tag Manager 163.5 kB · 52 ms CPU

Page health

Metric Current Previous Change Best Worst Trend
Main Thread Work 715 ms — — 715 ms 715 ms
Long Tasks 3 — — 3 3
DOM Elements 575 — — 575 575
Axe Violations Violating nodes from a full axe run — stricter than Lighthouse's subset 5 — — 5 5
A11y Failures 2 — — 2 2
A11y Failing Nodes 3 — — 3 3

Main thread work

script evaluation 258 ms
other 174 ms
style layout 167 ms
script parse compile 59 ms
parse HTML 36 ms
paint composite render 22 ms

Axe violations axe-core 4.13.0, full rule set

5 violating nodes across 3 rules, 545 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
  • serious link-in-text-block — Links must be distinguishable without relying on color 2 nodes
  • moderate heading-order — Heading levels should only increase by one 1 node

Accessibility failures 2 of 26 audits

Tracked as a count, not just the score — the weighted score is coarse enough that you can ship a broken component and barely move it.

  • link-in-text-block — Links rely on color to be distinguishable. 2 nodes
  • heading-order — Heading elements are not in a sequentially-descending order 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 20, 2026, 3:52 PM UTC 98 1.67 s 0.025 136 ms 344.8 kB 3/3 ±17 2,328 24.4s

Embed this score

Live below, then the markup that produces it. Drop that on any page to show blog.mozilla.org/addons'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://blog.mozilla.org/addons"></speedlify-score>