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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
84
GRADE
B
FIX
2
REVIEW
4
PASS
7
INFO
2

Performance-focused optimization plan with CWV assessment, top offenders, and time estimates

Mobile Desktop
96
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
100
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

1.05 s

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

1.12 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

58 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.001

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

1.05 s

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

1.78 s

Page Load Progression

444 ms
889 ms
1.3 s
1.8 s
2.2 s
2.7 s
3.1 s
3.6 s
Checks
15
7 PASS 4 REVIEW 2 FIX
D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (775.0 KiB of 775.2 KiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
HTTP Caching
Action
No cache headers
FIX
No cache headers
Warning::
No Cache-Control header found
Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

B
Image Optimization
24 images, 0 KB saveable
REVIEW
24 images, 0 KB saveable
Info::
All images are well-optimized
24 images 115 KB
0 oversized -0 KB
23 legacy format
0 missing dimensions CLS risk
B
JS Execution Cost
538ms total JS execution
REVIEW
538ms total JS execution
Info::
https://www.mozilla.org/en-US/: 143ms CPU time
Info::
Unattributable: 135ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-MQ77...: 124ms CPU time
Info::
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a4...: 77ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-MW3...: 59ms CPU time
Warning::
Third-party scripts: 538ms (100% of total)

Main Thread Breakdown

Script Evaluation 42% Other 24% Style & Layout 18% Script Parsing & Compilation 8%
ScriptTotalScriptingParse/CompileParty
https://www.mozilla.org/en-US/143ms4ms0ms3rd
Unattributable135ms5ms0ms3rd
https://www.googletagmanager.com/gtag/js?id=G-MQ7767QQQW&cx=c&gtm=4e64k1124ms100ms17ms3rd
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/ui.js77ms62ms12ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-MW3R8V&l=dataLayer59ms43ms12ms3rd
C
JS Bundles
Action
15 scripts, 202 KB unused
REVIEW
15 scripts, 202 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-MQ77...: 70 KB unused (39%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-MW3...: 59 KB unused (47%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a4...: 45 KB unused (46%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a4...: 27 KB unused (53%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 202 KB
202 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-MQ7767QQQW&cx=c&gtm=4e64k1177 KB70 KB (39%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-MW3R8V&l=dataLayer127 KB59 KB (47%)✓3rd
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/ui.js98 KB45 KB (46%)✓3rd
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/airgap.js53 KB27 KB (53%)✓3rd
https://www.mozilla.org/media/js/fxa.f30434397531.js3 KB—✓3rd
https://www.mozilla.org/media/js/lib.c244ff81b28a.js6 KB—✓3rd
https://www.mozilla.org/media/js/sentry.31edfa94a7f6.js19 KB—✓3rd
https://www.mozilla.org/media/js/data.a85f0425619e.js3 KB—✓3rd
https://www.mozilla.org/media/js/m24-ui.71f62c655696.js4 KB—✓3rd
https://www.mozilla.org/media/js/stub-attribution.819aeb6b157b.js3 KB—✓3rd

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

B
Page Weight Inventory
55 resources · 775 KB · 202 KB savings available
REVIEW
55 resources · 775 KB · 202 KB savings available
Info::
Within 1MB page-weight target
Got: 775 KB
Info::
~202 KB of savings available
Warning::
54 third-party resources (100% of weight)
55 resources · 775.2 KiB · 54 third-party Within 1MB page-weight target
JavaScript 65% · 501.7 KiB
Image 15% · 116.1 KiB
Font 14% · 107.2 KiB
CSS 3% · 25.3 KiB
Document 3% · 21.8 KiB
Other 0% · 3.0 KiB

~201.8 KiB of savings available

Remove unused JavaScript: 201.8 KiB
A
Page Weight Budget
775 KB transferred, 55 requests
PASS
775 KB transferred, 55 requests
Info::
Page weighs 2.0 MB (775 KB transferred)
Warning::
JavaScript is 502 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 502 KB
Info::
55 HTTP requests
Info::
Estimated 0.16 g CO2 per page load
775 KB / 2.4 MB budget
775 KB transferred
55 requests
0.16 g CO2 per page load
JavaScript 501.7 KiB 65%
Images 115.1 KiB 15%
Fonts 107.2 KiB 14%
CSS 25.3 KiB 3%
HTML 21.3 KiB 3%
Other 3.0 KiB 0%
Other 1.5 KiB 0%
0 2.4 MB 4.9 MB
Under budget

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

A+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Font Loading
4 fonts (107 KB)
PASS
4 fonts (107 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

107 KB total

Render-blocking

0

of 4

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 1.0 s LCP 1.1 shttps://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-SemiBold.b126cc23eddf.woff2MozillaText-SemiBold.b1... https://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-SemiBold.b126cc23eddf.woff2 — 26.3 KiB — 5 ms — font-display: swaphttps://www.mozilla.org/media/protocol/fonts/mozilla-headline/MozillaHeadline-SemiBold.bccc6c46c123.woff2MozillaHeadline-SemiBol... https://www.mozilla.org/media/protocol/fonts/mozilla-headline/MozillaHeadline-SemiBold.bccc6c46c123.woff2 — 28.4 KiB — 11 ms — font-display: swaphttps://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-Regular.71c103450d6d.woff2MozillaText-Regular.71c... https://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-Regular.71c103450d6d.woff2 — 26.3 KiB — 11 ms — font-display: swaphttps://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-Bold.4af7ce689fd6.woff2MozillaText-Bold.4af7ce... https://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-Bold.4af7ce689fd6.woff2 — 26.2 KiB — 11 ms — font-display: swap
MozillaText-SemiBold.b1... woff2 swap
Size 26 KB
Load time 5 ms
Start 771 ms
Risk FOUT — text flashes from fallback to web font
MozillaHeadline-SemiBol... woff2 swap
Size 28 KB
Load time 11 ms
Start 771 ms
Risk FOUT — text flashes from fallback to web font
MozillaText-Regular.71c... woff2 swap
Size 26 KB
Load time 11 ms
Start 772 ms
Risk FOUT — text flashes from fallback to web font
MozillaText-Bold.4af7ce... woff2 swap
Size 26 KB
Load time 11 ms
Start 772 ms
Risk FOUT — text flashes from fallback to web font
Optimization checklist
  • Preload critical fonts (priority=high)
  • Use woff2 format for all fonts
  • Set font-display to swap, optional, or fallback
  • Subset large fonts (≤100 KB each)
A+
Resource Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Google Cloud

Network Waterfall
55 requests over 1315ms
INFO
0 ms 500 ms 1.0 s FCP 1.0 s LCP 1.1 shttps://mozdev.org// https://mozdev.org/ — 301 — 137 B — 287 ms — h2https://www.mozilla.org/www.mozilla.org/ https://www.mozilla.org/ — 302 — 373 B — 14 ms — h2https://www.mozilla.org/en-US/www.mozilla.org/en-US/ https://www.mozilla.org/en-US/ — 200 — 21.3 KiB — 280 ms — h2https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/airgap.jstranscend-cdn.com/cm/d556c3a1-e57c-... https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/airgap.js — 200 — 52.5 KiB — 61 ms — h3https://www.mozilla.org/media/js/site.8f1217edbde0.jswww.mozilla.org/media/js/site.8f121... https://www.mozilla.org/media/js/site.8f1217edbde0.js — 200 — 2.6 KiB — 19 ms — h2https://www.mozilla.org/media/css/protocol-mozilla.54ea44c214ed.csswww.mozilla.org/media/css/protocol-... https://www.mozilla.org/media/css/protocol-mozilla.54ea44c214ed.css — 200 — 9.1 KiB — 12 ms — h2https://www.mozilla.org/media/css/m24-navigation-and-footer.038277dadfff.csswww.mozilla.org/media/css/m24-navig... https://www.mozilla.org/media/css/m24-navigation-and-footer.038277dadfff.css — 200 — 5.7 KiB — 18 ms — h2https://www.mozilla.org/media/css/m24-root.c79048453ab7.csswww.mozilla.org/media/css/m24-root.... https://www.mozilla.org/media/css/m24-root.c79048453ab7.css — 200 — 900 B — 17 ms — h2https://www.mozilla.org/media/css/m24-base.cb7020016bcf.csswww.mozilla.org/media/css/m24-base.... https://www.mozilla.org/media/css/m24-base.cb7020016bcf.css — 200 — 2.7 KiB — 19 ms — h2https://www.mozilla.org/media/css/m24-home.d8deebbf1639.csswww.mozilla.org/media/css/m24-home.... https://www.mozilla.org/media/css/m24-home.d8deebbf1639.css — 200 — 2.8 KiB — 20 ms — h2https://www.mozilla.org/media/js/gtm-snippet.b5b7c885f8fa.jswww.mozilla.org/media/js/gtm-snippe... https://www.mozilla.org/media/js/gtm-snippet.b5b7c885f8fa.js — 200 — 942 B — 17 ms — h2https://www.mozilla.org/media/img/home/2024/donate-720.0311101afe23.jpgwww.mozilla.org/media/img/home/2024... https://www.mozilla.org/media/img/home/2024/donate-720.0311101afe23.jpg — 200 — 90.2 KiB — 28 ms — h2https://www.mozilla.org/media/js/newsletter.988c40f6c26c.jswww.mozilla.org/media/js/newsletter... https://www.mozilla.org/media/js/newsletter.988c40f6c26c.js — 200 — 2.4 KiB — 10 ms — h2https://www.mozilla.org/media/js/sentry.31edfa94a7f6.jswww.mozilla.org/media/js/sentry.31e... https://www.mozilla.org/media/js/sentry.31edfa94a7f6.js — 200 — 19.4 KiB — 6 ms — h2https://www.mozilla.org/media/js/lib.c244ff81b28a.jswww.mozilla.org/media/js/lib.c244ff... https://www.mozilla.org/media/js/lib.c244ff81b28a.js — 200 — 5.9 KiB — 3 ms — h2https://www.mozilla.org/media/js/fxa.f30434397531.jswww.mozilla.org/media/js/fxa.f30434... https://www.mozilla.org/media/js/fxa.f30434397531.js — 200 — 2.5 KiB — 4 ms — h2https://www.mozilla.org/media/js/data.a85f0425619e.jswww.mozilla.org/media/js/data.a85f0... https://www.mozilla.org/media/js/data.a85f0425619e.js — 200 — 2.9 KiB — 4 ms — h2https://www.mozilla.org/media/js/m24-ui.71f62c655696.jswww.mozilla.org/media/js/m24-ui.71f... https://www.mozilla.org/media/js/m24-ui.71f62c655696.js — 200 — 4.2 KiB — 5 ms — h2https://www.mozilla.org/media/js/stub-attribution.819aeb6b157b.jswww.mozilla.org/media/js/stub-attri... https://www.mozilla.org/media/js/stub-attribution.819aeb6b157b.js — 200 — 2.8 KiB — 4 ms — h2https://www.mozilla.org/media/js/m24-animation.6371da6532a7.jswww.mozilla.org/media/js/m24-animat... https://www.mozilla.org/media/js/m24-animation.6371da6532a7.js — 200 — 648 B — 4 ms — h2https://www.mozilla.org/media/js/consent-banner.497ea1aa3e76.jswww.mozilla.org/media/js/consent-ba... https://www.mozilla.org/media/js/consent-banner.497ea1aa3e76.js — 200 — 2.4 KiB — 5 ms — h2https://www.mozilla.org/media/img/logos/m24/lockup-black.f2ddba3f0724.svgwww.mozilla.org/media/img/logos/m24... https://www.mozilla.org/media/img/logos/m24/lockup-black.f2ddba3f0724.svg — 200 — 1.0 KiB — 3 ms — h2https://www.mozilla.org/media/img/logos/mozilla/ads/Mozilla_Ads_Logo.6ed26d0eac2b.svgwww.mozilla.org/media/img/logos/moz... https://www.mozilla.org/media/img/logos/mozilla/ads/Mozilla_Ads_Logo.6ed26d0eac2b.svg — 200 — 1.5 KiB — 3 ms — h2https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/ui.jstranscend-cdn.com/cm/d556c3a1-e57c-... https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/ui.js — 200 — 98.4 KiB — 45 ms — h3https://www.googletagmanager.com/gtm.js?id=GTM-MW3R8V&l=dataLayerwww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-MW3R8V&l=dataLayer — 200 — 127.1 KiB — 77 ms — h2https://www.mozilla.org/media/protocol/img/logos/firefox/browser/logo.eb1324e44442.svgwww.mozilla.org/media/protocol/img/... https://www.mozilla.org/media/protocol/img/logos/firefox/browser/logo.eb1324e44442.svg — 200 — 2.9 KiB — 16 ms — h2https://www.mozilla.org/media/protocol/img/icons/arrow-right.a1e6e0252c06.svgwww.mozilla.org/media/protocol/img/... https://www.mozilla.org/media/protocol/img/icons/arrow-right.a1e6e0252c06.svg — 200 — 664 B — 13 ms — h2https://www.mozilla.org/media/img/logos/thunderbird/logo-thunderbird.121e9c0fed45.svgwww.mozilla.org/media/img/logos/thu... https://www.mozilla.org/media/img/logos/thunderbird/logo-thunderbird.121e9c0fed45.svg — 200 — 3.2 KiB — 17 ms — h2https://www.mozilla.org/media/protocol/img/logos/mozilla/vpn/logo.c648f487bfb8.svgwww.mozilla.org/media/protocol/img/... https://www.mozilla.org/media/protocol/img/logos/mozilla/vpn/logo.c648f487bfb8.svg — 200 — 940 B — 15 ms — h2https://www.mozilla.org/media/protocol/img/logos/firefox/monitor/logo.d97e5516f9e6.svgwww.mozilla.org/media/protocol/img/... https://www.mozilla.org/media/protocol/img/logos/firefox/monitor/logo.d97e5516f9e6.svg — 200 — 1.5 KiB — 8 ms — h2
0 ms 500 ms 1.0 s FCP 1.0 s LCP 1.1 shttps://mozdev.org// https://mozdev.org/ — 301 — 137 B — 287 ms — h2https://www.mozilla.org/www.mozilla.org/ https://www.mozilla.org/ — 302 — 373 B — 14 ms — h2https://www.mozilla.org/en-US/www.mozilla.org/en-US/ https://www.mozilla.org/en-US/ — 200 — 21.3 KiB — 280 ms — h2https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/airgap.jstranscend-cdn.com/cm/d556c3a1-e57c-... https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/airgap.js — 200 — 52.5 KiB — 61 ms — h3https://www.mozilla.org/media/js/site.8f1217edbde0.jswww.mozilla.org/media/js/site.8f121... https://www.mozilla.org/media/js/site.8f1217edbde0.js — 200 — 2.6 KiB — 19 ms — h2https://www.mozilla.org/media/css/protocol-mozilla.54ea44c214ed.csswww.mozilla.org/media/css/protocol-... https://www.mozilla.org/media/css/protocol-mozilla.54ea44c214ed.css — 200 — 9.1 KiB — 12 ms — h2https://www.mozilla.org/media/css/m24-navigation-and-footer.038277dadfff.csswww.mozilla.org/media/css/m24-navig... https://www.mozilla.org/media/css/m24-navigation-and-footer.038277dadfff.css — 200 — 5.7 KiB — 18 ms — h2https://www.mozilla.org/media/css/m24-root.c79048453ab7.csswww.mozilla.org/media/css/m24-root.... https://www.mozilla.org/media/css/m24-root.c79048453ab7.css — 200 — 900 B — 17 ms — h2https://www.mozilla.org/media/css/m24-base.cb7020016bcf.csswww.mozilla.org/media/css/m24-base.... https://www.mozilla.org/media/css/m24-base.cb7020016bcf.css — 200 — 2.7 KiB — 19 ms — h2https://www.mozilla.org/media/css/m24-home.d8deebbf1639.csswww.mozilla.org/media/css/m24-home.... https://www.mozilla.org/media/css/m24-home.d8deebbf1639.css — 200 — 2.8 KiB — 20 ms — h2https://www.mozilla.org/media/js/gtm-snippet.b5b7c885f8fa.jswww.mozilla.org/media/js/gtm-snippe... https://www.mozilla.org/media/js/gtm-snippet.b5b7c885f8fa.js — 200 — 942 B — 17 ms — h2https://www.mozilla.org/media/img/home/2024/donate-720.0311101afe23.jpgwww.mozilla.org/media/img/home/2024... https://www.mozilla.org/media/img/home/2024/donate-720.0311101afe23.jpg — 200 — 90.2 KiB — 28 ms — h2https://www.mozilla.org/media/js/newsletter.988c40f6c26c.jswww.mozilla.org/media/js/newsletter... https://www.mozilla.org/media/js/newsletter.988c40f6c26c.js — 200 — 2.4 KiB — 10 ms — h2https://www.mozilla.org/media/js/sentry.31edfa94a7f6.jswww.mozilla.org/media/js/sentry.31e... https://www.mozilla.org/media/js/sentry.31edfa94a7f6.js — 200 — 19.4 KiB — 6 ms — h2https://www.mozilla.org/media/js/lib.c244ff81b28a.jswww.mozilla.org/media/js/lib.c244ff... https://www.mozilla.org/media/js/lib.c244ff81b28a.js — 200 — 5.9 KiB — 3 ms — h2https://www.mozilla.org/media/js/fxa.f30434397531.jswww.mozilla.org/media/js/fxa.f30434... https://www.mozilla.org/media/js/fxa.f30434397531.js — 200 — 2.5 KiB — 4 ms — h2https://www.mozilla.org/media/js/data.a85f0425619e.jswww.mozilla.org/media/js/data.a85f0... https://www.mozilla.org/media/js/data.a85f0425619e.js — 200 — 2.9 KiB — 4 ms — h2https://www.mozilla.org/media/js/m24-ui.71f62c655696.jswww.mozilla.org/media/js/m24-ui.71f... https://www.mozilla.org/media/js/m24-ui.71f62c655696.js — 200 — 4.2 KiB — 5 ms — h2https://www.mozilla.org/media/js/stub-attribution.819aeb6b157b.jswww.mozilla.org/media/js/stub-attri... https://www.mozilla.org/media/js/stub-attribution.819aeb6b157b.js — 200 — 2.8 KiB — 4 ms — h2https://www.mozilla.org/media/js/m24-animation.6371da6532a7.jswww.mozilla.org/media/js/m24-animat... https://www.mozilla.org/media/js/m24-animation.6371da6532a7.js — 200 — 648 B — 4 ms — h2https://www.mozilla.org/media/js/consent-banner.497ea1aa3e76.jswww.mozilla.org/media/js/consent-ba... https://www.mozilla.org/media/js/consent-banner.497ea1aa3e76.js — 200 — 2.4 KiB — 5 ms — h2https://www.mozilla.org/media/img/logos/m24/lockup-black.f2ddba3f0724.svgwww.mozilla.org/media/img/logos/m24... https://www.mozilla.org/media/img/logos/m24/lockup-black.f2ddba3f0724.svg — 200 — 1.0 KiB — 3 ms — h2https://www.mozilla.org/media/img/logos/mozilla/ads/Mozilla_Ads_Logo.6ed26d0eac2b.svgwww.mozilla.org/media/img/logos/moz... https://www.mozilla.org/media/img/logos/mozilla/ads/Mozilla_Ads_Logo.6ed26d0eac2b.svg — 200 — 1.5 KiB — 3 ms — h2https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/ui.jstranscend-cdn.com/cm/d556c3a1-e57c-... https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/ui.js — 200 — 98.4 KiB — 45 ms — h3https://www.googletagmanager.com/gtm.js?id=GTM-MW3R8V&l=dataLayerwww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-MW3R8V&l=dataLayer — 200 — 127.1 KiB — 77 ms — h2https://www.mozilla.org/media/protocol/img/logos/firefox/browser/logo.eb1324e44442.svgwww.mozilla.org/media/protocol/img/... 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h2https://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-SemiBold.b126cc23eddf.woff2www.mozilla.org/media/protocol/font... https://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-SemiBold.b126cc23eddf.woff2 — 200 — 26.3 KiB — 5 ms — h2https://www.mozilla.org/media/protocol/fonts/mozilla-headline/MozillaHeadline-SemiBold.bccc6c46c123.woff2www.mozilla.org/media/protocol/font... https://www.mozilla.org/media/protocol/fonts/mozilla-headline/MozillaHeadline-SemiBold.bccc6c46c123.woff2 — 200 — 28.4 KiB — 11 ms — h2https://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-Regular.71c103450d6d.woff2www.mozilla.org/media/protocol/font... https://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-Regular.71c103450d6d.woff2 — 200 — 26.3 KiB — 11 ms — h2https://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-Bold.4af7ce689fd6.woff2www.mozilla.org/media/protocol/font... https://www.mozilla.org/media/protocol/fonts/mozilla-text/MozillaText-Bold.4af7ce689fd6.woff2 — 200 — 26.2 KiB — 11 ms — h2https://www.mozilla.org/media/img/icons/m24-small/glasses.8c98d766725a.svgwww.mozilla.org/media/img/icons/m24... https://www.mozilla.org/media/img/icons/m24-small/glasses.8c98d766725a.svg — 200 — 1012 B — 9 ms — h2https://www.mozilla.org/media/img/icons/m24-small/arrow-right.81a74c691dc2.svgwww.mozilla.org/media/img/icons/m24... https://www.mozilla.org/media/img/icons/m24-small/arrow-right.81a74c691dc2.svg — 200 — 535 B — 13 ms — h2https://www.mozilla.org/media/img/icons/social/bluesky/white.8fd522097881.svgwww.mozilla.org/media/img/icons/soc... https://www.mozilla.org/media/img/icons/social/bluesky/white.8fd522097881.svg — 200 — 887 B — 18 ms — h2https://www.mozilla.org/media/protocol/img/icons/social/instagram/white.a7014a6150b3.svgwww.mozilla.org/media/protocol/img/... https://www.mozilla.org/media/protocol/img/icons/social/instagram/white.a7014a6150b3.svg — 200 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h2https://www.google-analytics.com/g/collect?v=2&tid=G-MQ7767QQQW&gtm=45je64k1v877483787z871075029za20gzb71075029zd71075029&_p=1776897477583&gcd=13l3l3l3l1l1&npa=0&dma=0&are=1&cid=1221071331.1776897478&frm=0&pscdl=noapi&rcb=4&sr=800x600&uaa=x86&uab=64&uafvl=Not-A.Brand%3B24.0.0.0%7CChromium%3B146.0.7680.164&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115938466~115938468~117266401~117512542&sid=1776897478&sct=1&seg=0&dl=https%3A%2F%2Fwww.mozilla.org%2Fen-US%2F&dt=Mozilla%20-%20Internet%20for%20people%2C%20not%20profit%20(US)&en=page_view&_fv=1&_nsi=1&_ss=1&tfd=1270www.google-analytics.com/g/collect?... 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h2https://www.googletagmanager.com/a?v=3&t=l&pid=1997184867&rv=64k1&tag_exp=0~115938466~115938468~117266401~117512542&u=AAAAAAAIIAAAACAg&ut=Ag&h=Ag&gtm=45je64k1v877483787za20gzb71075029zd71075029&cl=3.11.0&ccid=77483787&cid=G-MQ7767QQQW&l=L708.S85.B68.E90.I1029.TC24.HTC0.F836.C3~gtm.init_consent.S3.V2.E82.TS5ogtdma.TI110.TE1~gtm.init.S0.V0.E76.TS5ogtcrossdomain.TI107.TE0.TS5ogtreferralexclusion.TI109.TE0.TS5ogt1pdatav2.TI112.TE0.TS5ccdgafirst.TI131.TE0.TS5setproductsettings.TI130.TE0.TS5ccdgaregscope.TI129.TE10.TS5ccdemdownload.TI128.TE1.TS5ccdemform.TI127.TE1.TS5ccdemoutboundclick.TI126.TE0.TS5ccdempageview.TI125.TE1.TS5ccdemscroll.TI124.TE1.TS5ccdemsitesearch.TI123.TE0.TS5ccdemvideo.TI122.TE1.TS5ccdconversionmarking.TI121.TE0.TS5ogteventcreate.TI120.TE0.TS5ogteventcreate.TI119.TE0.TS5ogteventcreate.TI118.TE0.TS5ogteventcreate.TI117.TE0.TS5ogteventcreate.TI116.TE0.TS5ccdautoredact.TI115.TE0.TS5ccdgaadslink.TI114.TE0.TS5ccdgalast.TI113.TE0~gtm.js.S0.V0.E45.TS5gct.TI105.TE1~gtm.dom.S0.V0.E10~*.S0.V0.E3~gtm.load.S0.V0.E1~GA564www.googletagmanager.com/a?v=3&t=l&... 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— 200 — 11 B — 17 ms — h3https://www.mozilla.org/media/img/favicons/mozilla/favicon.d0be64e474b1.icowww.mozilla.org/media/img/favicons/... https://www.mozilla.org/media/img/favicons/mozilla/favicon.d0be64e474b1.ico — 200 — 1.0 KiB — 5 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
100% of JavaScript execution is third-party
First-party Third-party 538ms · 424KB · €6/mo
www.mozilla.org
Other
Optional
Execution 143ms
Transfer 21 KB
Monthly Cost €2/mo
Unattributable
Other
Optional
Execution 135ms
Transfer 0 KB
Monthly Cost €1/mo
Google Tag Manager
Tag Manager
Optional
Execution 124ms
Transfer 177 KB
Unused 39%
Monthly Cost €1/mo
transcend-cdn.com
Other
Optional
Execution 77ms
Transfer 98 KB
Unused 46%
Monthly Cost €1/mo
Google Tag Manager
Tag Manager
Optional
Execution 59ms
Transfer 127 KB
Unused 47%
Monthly Cost €1/mo

100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.

Why this matters

When third-party JS execution time exceeds your own, performance gains from frontend work are capped by code you don't own.

Learn more ▾

Every millisecond of third-party JS competes with your own for main-thread time. If their share is bigger than yours, optimization on your code base barely moves the needle. Audit, defer, or remove third-parties before further frontend optimization. Use Lighthouse's third-party audit to identify the worst offenders.

Source: web.dev

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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