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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
88
GRADE
B
FIX
1
REVIEW
2
PASS
10
INFO
2

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

Mobile Desktop
88
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.

1.52 s

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

1.53 s

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

6 ms

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

0.000

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

1.52 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.

1.72 s

Page Load Progression

419 ms
839 ms
1.3 s
1.7 s
2.1 s
2.5 s
2.9 s
3.4 s
Checks
15
10 PASS 2 REVIEW 1 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 (470.6 KiB of 470.8 KiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
B
Image Optimization
23 images, 0 KB saveable
REVIEW
23 images, 0 KB saveable
Info::
All images are well-optimized
23 images 115 KB
0 oversized -0 KB
22 legacy format
0 missing dimensions CLS risk
B
JS Bundles
13 scripts, 73 KB unused
REVIEW
13 scripts, 73 KB unused
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...: 28 KB unused (54%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 73 KB
73 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/ui.js99 KB45 KB (46%)✓3rd
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/airgap.js52 KB28 KB (54%)✓3rd
https://www.mozilla.org/media/js/fxa.f30434397531.js3 KB—✓3rd
https://www.mozilla.org/media/js/newsletter.988c40f6c26c.js2 KB—✓3rd
https://www.mozilla.org/media/js/sentry.31edfa94a7f6.js19 KB—✓3rd
https://www.mozilla.org/media/js/lib.c244ff81b28a.js6 KB—✓3rd
https://www.mozilla.org/media/js/gtm-snippet.b5b7c885f8fa.js1 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

A+
Page Weight Budget
471 KB transferred, 51 requests
PASS
471 KB transferred, 51 requests
Info::
Page weighs 1.1 MB (471 KB transferred)
Info::
51 HTTP requests
Info::
Estimated 0.10 g CO2 per page load
471 KB / 2.4 MB budget
471 KB transferred
51 requests
0.10 g CO2 per page load
JavaScript 197.8 KiB 42%
Images 115.0 KiB 24%
Fonts 107.2 KiB 23%
CSS 25.4 KiB 5%
HTML 21.3 KiB 5%
Other 2.5 KiB 1%
Other 1.6 KiB 0%
0 2.4 MB 4.9 MB
Under budget
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+
JS Execution Cost
290ms total JS execution
PASS
290ms total JS execution
Info::
Unattributable: 84ms CPU time
Info::
https://www.mozilla.org/media/js/newsletter.988c40...: 74ms CPU time
Info::
https://www.mozilla.org/en-US/: 68ms CPU time
Info::
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a4...: 64ms CPU time
Warning::
Third-party scripts: 290ms (100% of total)

Main Thread Breakdown

Style & Layout 33% Other 31% Script Evaluation 24% Script Parsing & Compilation 5%
ScriptTotalScriptingParse/CompileParty
Unattributable84ms3ms0ms3rd
https://www.mozilla.org/media/js/newsletter.988c40f6c26c.js74ms1ms0ms3rd
https://www.mozilla.org/en-US/68ms2ms0ms3rd
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/ui.js64ms47ms9ms3rd
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 1.5 s FCP 1.5 s LCP 1.5 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 — 26.1 KiB — 16 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 — 28.6 KiB — 7 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 — 26.2 KiB — 7 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 — 26.4 KiB — 12 ms — font-display: swap
MozillaText-SemiBold.b1... woff2 swap
Size 26 KB
Load time 16 ms
Start 889 ms
Risk FOUT — text flashes from fallback to web font
MozillaHeadline-SemiBol... woff2 swap
Size 29 KB
Load time 7 ms
Start 891 ms
Risk FOUT — text flashes from fallback to web font
MozillaText-Regular.71c... woff2 swap
Size 26 KB
Load time 7 ms
Start 891 ms
Risk FOUT — text flashes from fallback to web font
MozillaText-Bold.4af7ce... woff2 swap
Size 26 KB
Load time 12 ms
Start 892 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
Page Weight Inventory
51 resources · 471 KB · 73 KB savings available
PASS
51 resources · 471 KB · 73 KB savings available
Info::
Within 1MB page-weight target
Got: 471 KB
Info::
~73 KB of savings available
Warning::
50 third-party resources (100% of weight)
51 resources · 470.8 KiB · 50 third-party Within 1MB page-weight target
JavaScript 42% · 197.8 KiB
Image 25% · 116.0 KiB
Font 23% · 107.2 KiB
CSS 5% · 25.4 KiB
Document 5% · 21.9 KiB
Other 1% · 2.5 KiB

~73.3 KiB of savings available

Remove unused JavaScript: 73.3 KiB
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

A
HTTP Caching
max-age=3600 (1 hour)
PASS
max-age=3600 (1 hour)
Info::
Cache-Control header is set
Got: max-age=3600
Info::
Effective TTL: 1 hour (max-age=3600)
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

max-age=3600

DirectiveValueMeaning
max-age3600Cache for 1 hour
Effective TTL: 3600 seconds
Network Waterfall
51 requests over 1073ms
INFO
0 ms 500 ms 1.0 s 1.5 s FCP 1.5 s LCP 1.5 shttps://mozilla.org// https://mozilla.org/ — 301 — 165 B — 604 ms — h2https://www.mozilla.org/www.mozilla.org/ https://www.mozilla.org/ — 302 — 383 B — 28 ms — h2https://www.mozilla.org/en-US/www.mozilla.org/en-US/ https://www.mozilla.org/en-US/ — 200 — 21.3 KiB — 3 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 — 52.3 KiB — 110 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 — 2.7 KiB — 5 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 — 19 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 — 5.5 KiB — 23 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 — 1.1 KiB — 20 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 — 19 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 — 1.1 KiB — 23 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 — 90.1 KiB — 26 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 — 2.2 KiB — 24 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 — 3 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 — 5.8 KiB — 4 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 — 2.6 KiB — 2 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 — 3.0 KiB — 2 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 — 2 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 — 2.9 KiB — 2 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 — 641 B — 2 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 — 3 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 — 2 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 — 1.6 KiB — 2 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 — 98.7 KiB — 124 ms — h3https://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 — 8 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 — 668 B — 16 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 — 3.3 KiB — 14 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 — 933 B — 13 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 — 13 ms — h2https://www.mozilla.org/media/protocol/img/logos/firefox/relay/logo.d42a8b52e44c.svgwww.mozilla.org/media/protocol/img/... https://www.mozilla.org/media/protocol/img/logos/firefox/relay/logo.d42a8b52e44c.svg — 200 — 2.0 KiB — 14 ms — h2
0 ms 500 ms 1.0 s 1.5 s FCP 1.5 s LCP 1.5 shttps://mozilla.org// https://mozilla.org/ — 301 — 165 B — 604 ms — h2https://www.mozilla.org/www.mozilla.org/ https://www.mozilla.org/ — 302 — 383 B — 28 ms — h2https://www.mozilla.org/en-US/www.mozilla.org/en-US/ https://www.mozilla.org/en-US/ — 200 — 21.3 KiB — 3 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 — 52.3 KiB — 110 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 — 2.7 KiB — 5 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 — 19 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 — 5.5 KiB — 23 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 — 1.1 KiB — 20 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 — 19 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 — 1.1 KiB — 23 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 — 90.1 KiB — 26 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 — 2.2 KiB — 24 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 — 3 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 — 5.8 KiB — 4 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 — 2.6 KiB — 2 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 — 3.0 KiB — 2 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 — 2 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 — 2.9 KiB — 2 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 — 641 B — 2 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 — 3 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 — 2 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 — 1.6 KiB — 2 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 — 98.7 KiB — 124 ms — h3https://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 — 8 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 — 668 B — 16 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 — 3.3 KiB — 14 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 — 933 B — 13 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 — 13 ms — 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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 — 2 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 290ms · 122KB · €3/mo
Unattributable
Other
Optional
Execution 84ms
Transfer 0 KB
Monthly Cost €1/mo
www.mozilla.org
Other
Optional
Execution 74ms
Transfer 2 KB
Monthly Cost €1/mo
www.mozilla.org
Other
Optional
Execution 68ms
Transfer 21 KB
Monthly Cost €1/mo
transcend-cdn.com
Other
Optional
Execution 64ms
Transfer 99 KB
Unused 46%
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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