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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
86
GRADE
B
FIX
2
REVIEW
3
PASS
8
INFO
2

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

Mobile Desktop
95
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.
92
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.

979 ms

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

1.26 s

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

40 ms

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

0.052

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

979 ms

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

1.26 s

Page Load Progression

375 ms
750 ms
1.1 s
1.5 s
1.9 s
2.2 s
2.6 s
3.0 s
Checks
15
8 PASS 3 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 (503.3 KiB of 503.4 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
18 images, 0 KB saveable
REVIEW
18 images, 0 KB saveable
Info::
All images are well-optimized
18 images 110 KB
0 oversized -0 KB
18 legacy format
0 missing dimensions CLS risk
B
JS Execution Cost
698ms total JS execution
REVIEW
698ms total JS execution
Warning::
https://www.firefox.com/en-US/: 402ms CPU time
Info::
Unattributable: 179ms CPU time
Info::
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a4...: 117ms CPU time
Warning::
Third-party scripts: 698ms (100% of total)

Main Thread Breakdown

Other 40% Script Evaluation 22% Style & Layout 21% Rendering 9% Script Parsing & Compilation 4%
ScriptTotalScriptingParse/CompileParty
https://www.firefox.com/en-US/402ms7ms0ms3rd
Unattributable179ms7ms0ms3rd
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/ui.js117ms91ms19ms3rd
B
JS Bundles
14 scripts, 73 KB unused
REVIEW
14 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.firefox.com/media/js/firefox-cms-flare26.c214e922a79f.js25 KB—✓3rd
https://www.firefox.com/media/js/sentry.2f57b70e06a9.js19 KB—✓3rd
https://www.firefox.com/media/js/lib.244fb6035eee.js6 KB—✓3rd
https://www.firefox.com/media/js/data.66a011d9be0e.js2 KB—✓3rd
https://www.firefox.com/media/js/gtm-snippet.75f2d1f2194b.js1 KB—✓3rd
https://www.firefox.com/media/js/ui-tour-buttons.5f82dc085f31.js1 KB—✓3rd
https://www.firefox.com/media/js/flare-navigation.17c4a3a73443.js9 KB—✓3rd
https://www.firefox.com/media/js/flare-lang-switcher.90adb422979f.js1 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
503 KB transferred, 42 requests
PASS
503 KB transferred, 42 requests
Info::
Page weighs 1.4 MB (503 KB transferred)
Info::
42 HTTP requests
Info::
Estimated 0.10 g CO2 per page load
503 KB / 2.4 MB budget
503 KB transferred
42 requests
0.10 g CO2 per page load
JavaScript 224.7 KiB 45%
Images 110.2 KiB 22%
Fonts 101.4 KiB 20%
CSS 40.7 KiB 8%
HTML 15.2 KiB 3%
Other 8.8 KiB 2%
Other 2.5 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+
Font Loading
2 fonts (101 KB)
PASS
2 fonts (101 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

101 KB total

Render-blocking

0

of 2

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 979 ms LCP 1.3 shttps://www.firefox.com/media/fonts/mozilla-headline/MozillaHeadline-Variable.19ade5d17bd1.woff2MozillaHeadline-Variabl... https://www.firefox.com/media/fonts/mozilla-headline/MozillaHeadline-Variable.19ade5d17bd1.woff2 — 68.4 KiB — 21 ms — font-display: swaphttps://www.firefox.com/media/fonts/mozilla-text/MozillaText-Variable.fc7317808d75.woff2MozillaText-Variable.fc... https://www.firefox.com/media/fonts/mozilla-text/MozillaText-Variable.fc7317808d75.woff2 — 33.0 KiB — 14 ms — font-display: swap
MozillaHeadline-Variabl... woff2 swap
Size 68 KB
Load time 21 ms
Start 522 ms
Risk FOUT — text flashes from fallback to web font
MozillaText-Variable.fc... woff2 swap
Size 33 KB
Load time 14 ms
Start 522 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
42 resources · 503 KB · 73 KB savings available
PASS
42 resources · 503 KB · 73 KB savings available
Info::
Within 1MB page-weight target
Got: 503 KB
Info::
~73 KB of savings available
Warning::
41 third-party resources (100% of weight)
42 resources · 503.4 KiB · 41 third-party Within 1MB page-weight target
JavaScript 45% · 224.7 KiB
Image 24% · 118.5 KiB
Font 20% · 101.4 KiB
CSS 8% · 40.7 KiB
Document 3% · 15.7 KiB
Other 0% · 2.5 KiB

~73.2 KiB of savings available

Remove unused JavaScript: 73.2 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

Network Waterfall
42 requests over 862ms
INFO
0 ms 500 ms 1.0 s FCP 979 ms LCP 1.3 shttps://firefox.com// https://firefox.com/ — 302 — 139 B — 161 ms — h2https://www.firefox.com/www.firefox.com/ https://www.firefox.com/ — 302 — 393 B — 14 ms — h2https://www.firefox.com/en-US/www.firefox.com/en-US/ https://www.firefox.com/en-US/ — 200 — 15.2 KiB — 9 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 — 52.4 KiB — 63 ms — h3https://www.firefox.com/media/css/flare26.b59da170eadc.csswww.firefox.com/media/css/flare26.b... https://www.firefox.com/media/css/flare26.b59da170eadc.css — 200 — 32.8 KiB — 28 ms — h2https://www.firefox.com/media/js/site.4dabcff0fc9f.jswww.firefox.com/media/js/site.4dabc... https://www.firefox.com/media/js/site.4dabcff0fc9f.js — 200 — 2.6 KiB — 20 ms — h2https://www.firefox.com/media/js/gtm-snippet.75f2d1f2194b.jswww.firefox.com/media/js/gtm-snippe... https://www.firefox.com/media/js/gtm-snippet.75f2d1f2194b.js — 200 — 1.2 KiB — 20 ms — h2https://www.firefox.com/media/js/sentry.2f57b70e06a9.jswww.firefox.com/media/js/sentry.2f5... https://www.firefox.com/media/js/sentry.2f57b70e06a9.js — 200 — 19.4 KiB — 23 ms — h2https://www.firefox.com/media/js/lib.244fb6035eee.jswww.firefox.com/media/js/lib.244fb6... https://www.firefox.com/media/js/lib.244fb6035eee.js — 200 — 5.7 KiB — 20 ms — h2https://www.firefox.com/media/js/data.66a011d9be0e.jswww.firefox.com/media/js/data.66a01... https://www.firefox.com/media/js/data.66a011d9be0e.js — 200 — 2.1 KiB — 6 ms — h2https://www.firefox.com/media/js/firefox-cms-flare26.c214e922a79f.jswww.firefox.com/media/js/firefox-cm... https://www.firefox.com/media/js/firefox-cms-flare26.c214e922a79f.js — 200 — 24.8 KiB — 10 ms — h2https://www.firefox.com/media/js/ui-tour-buttons.5f82dc085f31.jswww.firefox.com/media/js/ui-tour-bu... https://www.firefox.com/media/js/ui-tour-buttons.5f82dc085f31.js — 200 — 1.0 KiB — 8 ms — h2https://www.firefox.com/media/js/flare-navigation.17c4a3a73443.jswww.firefox.com/media/js/flare-navi... https://www.firefox.com/media/js/flare-navigation.17c4a3a73443.js — 200 — 9.4 KiB — 8 ms — h2https://www.firefox.com/media/js/flare-lang-switcher.90adb422979f.jswww.firefox.com/media/js/flare-lang... https://www.firefox.com/media/js/flare-lang-switcher.90adb422979f.js — 200 — 768 B — 7 ms — h2https://www.firefox.com/media/js/consent-banner.35e30dbc9f8f.jswww.firefox.com/media/js/consent-ba... https://www.firefox.com/media/js/consent-banner.35e30dbc9f8f.js — 200 — 2.5 KiB — 5 ms — h2https://www.firefox.com/media/js/stub-attribution.502fd79d417f.jswww.firefox.com/media/js/stub-attri... https://www.firefox.com/media/js/stub-attribution.502fd79d417f.js — 200 — 2.9 KiB — 7 ms — h2https://www.firefox.com/media/js/download_as_default.740bb0ac58b9.jswww.firefox.com/media/js/download_a... https://www.firefox.com/media/js/download_as_default.740bb0ac58b9.js — 200 — 1.4 KiB — 8 ms — h2https://www.firefox.com/media/img/logos/firefox/logo-word-hor-2026.svgwww.firefox.com/media/img/logos/fir... https://www.firefox.com/media/img/logos/firefox/logo-word-hor-2026.svg — 200 — 5.5 KiB — 4 ms — h2https://www.firefox.com/media/img/l10n/en-US/firefox/ios/btn-app-store.1cfd5dba4a92.svgwww.firefox.com/media/img/l10n/en-U... https://www.firefox.com/media/img/l10n/en-US/firefox/ios/btn-app-store.1cfd5dba4a92.svg — 200 — 4.8 KiB — 21 ms — h2https://www.firefox.com/media/img/l10n/en-US/firefox/android/btn-google-play.77bdbc935c58.pngwww.firefox.com/media/img/l10n/en-U... https://www.firefox.com/media/img/l10n/en-US/firefox/android/btn-google-play.77bdbc935c58.png — 200 — 3.0 KiB — 11 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 — 98.6 KiB — 61 ms — h3https://www.firefox.com/media/css/flare26_base.6222ecc62b3a.csswww.firefox.com/media/css/flare26_b... https://www.firefox.com/media/css/flare26_base.6222ecc62b3a.css — 200 — 3.7 KiB — 7 ms — h2https://www.firefox.com/media/img/logos/firefox/logo-word-hor-white-2026.38b0d9aa301a.svgwww.firefox.com/media/img/logos/fir... https://www.firefox.com/media/img/logos/firefox/logo-word-hor-white-2026.38b0d9aa301a.svg — 200 — 5.3 KiB — 11 ms — h2https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/arrows-and-chevrons/chevron-down-16.e2f145363ee8.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/arrows-and-chevrons/chevron-down-16.e2f145363ee8.svg — 200 — 761 B — 12 ms — h2https://www.firefox.com/media/img/firefox/flare/kit-dive.26257f27e8a0.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/kit-dive.26257f27e8a0.svg — 200 — 6.0 KiB — 17 ms — h2https://www.firefox.com/media/img/firefox/flare/sitting-kit-2.f9dedcdd542b.pngwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/sitting-kit-2.f9dedcdd542b.png — 200 — 63.9 KiB — 24 ms — h2https://www.firefox.com/media/img/icons/external.e2b4246cf764.svgwww.firefox.com/media/img/icons/ext... https://www.firefox.com/media/img/icons/external.e2b4246cf764.svg — 200 — 723 B — 19 ms — h2https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/globe/globe-16.74af97ffa793.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/globe/globe-16.74af97ffa793.svg — 200 — 855 B — 19 ms — h2https://www.firefox.com/media/img/firefox/flare/kit-tail-2.1608e2bf46c5.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/kit-tail-2.1608e2bf46c5.svg — 200 — 7.5 KiB — 7 ms — h2https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/downloads/downloads-16.20e252d0a92b.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/downloads/downloads-16.20e252d0a92b.svg — 200 — 685 B — 3 ms — h2
0 ms 500 ms 1.0 s FCP 979 ms LCP 1.3 shttps://firefox.com// https://firefox.com/ — 302 — 139 B — 161 ms — h2https://www.firefox.com/www.firefox.com/ https://www.firefox.com/ — 302 — 393 B — 14 ms — h2https://www.firefox.com/en-US/www.firefox.com/en-US/ https://www.firefox.com/en-US/ — 200 — 15.2 KiB — 9 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 — 52.4 KiB — 63 ms — h3https://www.firefox.com/media/css/flare26.b59da170eadc.csswww.firefox.com/media/css/flare26.b... https://www.firefox.com/media/css/flare26.b59da170eadc.css — 200 — 32.8 KiB — 28 ms — h2https://www.firefox.com/media/js/site.4dabcff0fc9f.jswww.firefox.com/media/js/site.4dabc... https://www.firefox.com/media/js/site.4dabcff0fc9f.js — 200 — 2.6 KiB — 20 ms — h2https://www.firefox.com/media/js/gtm-snippet.75f2d1f2194b.jswww.firefox.com/media/js/gtm-snippe... https://www.firefox.com/media/js/gtm-snippet.75f2d1f2194b.js — 200 — 1.2 KiB — 20 ms — h2https://www.firefox.com/media/js/sentry.2f57b70e06a9.jswww.firefox.com/media/js/sentry.2f5... https://www.firefox.com/media/js/sentry.2f57b70e06a9.js — 200 — 19.4 KiB — 23 ms — h2https://www.firefox.com/media/js/lib.244fb6035eee.jswww.firefox.com/media/js/lib.244fb6... https://www.firefox.com/media/js/lib.244fb6035eee.js — 200 — 5.7 KiB — 20 ms — h2https://www.firefox.com/media/js/data.66a011d9be0e.jswww.firefox.com/media/js/data.66a01... https://www.firefox.com/media/js/data.66a011d9be0e.js — 200 — 2.1 KiB — 6 ms — h2https://www.firefox.com/media/js/firefox-cms-flare26.c214e922a79f.jswww.firefox.com/media/js/firefox-cm... https://www.firefox.com/media/js/firefox-cms-flare26.c214e922a79f.js — 200 — 24.8 KiB — 10 ms — h2https://www.firefox.com/media/js/ui-tour-buttons.5f82dc085f31.jswww.firefox.com/media/js/ui-tour-bu... https://www.firefox.com/media/js/ui-tour-buttons.5f82dc085f31.js — 200 — 1.0 KiB — 8 ms — h2https://www.firefox.com/media/js/flare-navigation.17c4a3a73443.jswww.firefox.com/media/js/flare-navi... https://www.firefox.com/media/js/flare-navigation.17c4a3a73443.js — 200 — 9.4 KiB — 8 ms — h2https://www.firefox.com/media/js/flare-lang-switcher.90adb422979f.jswww.firefox.com/media/js/flare-lang... https://www.firefox.com/media/js/flare-lang-switcher.90adb422979f.js — 200 — 768 B — 7 ms — h2https://www.firefox.com/media/js/consent-banner.35e30dbc9f8f.jswww.firefox.com/media/js/consent-ba... https://www.firefox.com/media/js/consent-banner.35e30dbc9f8f.js — 200 — 2.5 KiB — 5 ms — h2https://www.firefox.com/media/js/stub-attribution.502fd79d417f.jswww.firefox.com/media/js/stub-attri... https://www.firefox.com/media/js/stub-attribution.502fd79d417f.js — 200 — 2.9 KiB — 7 ms — h2https://www.firefox.com/media/js/download_as_default.740bb0ac58b9.jswww.firefox.com/media/js/download_a... https://www.firefox.com/media/js/download_as_default.740bb0ac58b9.js — 200 — 1.4 KiB — 8 ms — h2https://www.firefox.com/media/img/logos/firefox/logo-word-hor-2026.svgwww.firefox.com/media/img/logos/fir... https://www.firefox.com/media/img/logos/firefox/logo-word-hor-2026.svg — 200 — 5.5 KiB — 4 ms — h2https://www.firefox.com/media/img/l10n/en-US/firefox/ios/btn-app-store.1cfd5dba4a92.svgwww.firefox.com/media/img/l10n/en-U... https://www.firefox.com/media/img/l10n/en-US/firefox/ios/btn-app-store.1cfd5dba4a92.svg — 200 — 4.8 KiB — 21 ms — h2https://www.firefox.com/media/img/l10n/en-US/firefox/android/btn-google-play.77bdbc935c58.pngwww.firefox.com/media/img/l10n/en-U... https://www.firefox.com/media/img/l10n/en-US/firefox/android/btn-google-play.77bdbc935c58.png — 200 — 3.0 KiB — 11 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 — 98.6 KiB — 61 ms — h3https://www.firefox.com/media/css/flare26_base.6222ecc62b3a.csswww.firefox.com/media/css/flare26_b... https://www.firefox.com/media/css/flare26_base.6222ecc62b3a.css — 200 — 3.7 KiB — 7 ms — h2https://www.firefox.com/media/img/logos/firefox/logo-word-hor-white-2026.38b0d9aa301a.svgwww.firefox.com/media/img/logos/fir... https://www.firefox.com/media/img/logos/firefox/logo-word-hor-white-2026.38b0d9aa301a.svg — 200 — 5.3 KiB — 11 ms — h2https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/arrows-and-chevrons/chevron-down-16.e2f145363ee8.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/arrows-and-chevrons/chevron-down-16.e2f145363ee8.svg — 200 — 761 B — 12 ms — h2https://www.firefox.com/media/img/firefox/flare/kit-dive.26257f27e8a0.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/kit-dive.26257f27e8a0.svg — 200 — 6.0 KiB — 17 ms — h2https://www.firefox.com/media/img/firefox/flare/sitting-kit-2.f9dedcdd542b.pngwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/sitting-kit-2.f9dedcdd542b.png — 200 — 63.9 KiB — 24 ms — h2https://www.firefox.com/media/img/icons/external.e2b4246cf764.svgwww.firefox.com/media/img/icons/ext... https://www.firefox.com/media/img/icons/external.e2b4246cf764.svg — 200 — 723 B — 19 ms — h2https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/globe/globe-16.74af97ffa793.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/globe/globe-16.74af97ffa793.svg — 200 — 855 B — 19 ms — h2https://www.firefox.com/media/img/firefox/flare/kit-tail-2.1608e2bf46c5.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/kit-tail-2.1608e2bf46c5.svg — 200 — 7.5 KiB — 7 ms — h2https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/downloads/downloads-16.20e252d0a92b.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/downloads/downloads-16.20e252d0a92b.svg — 200 — 685 B — 3 ms — h2https://www.firefox.com/media/img/firefox/flare/fox-brand-curious.3ea99c60c166.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/fox-brand-curious.3ea99c60c166.svg — 200 — 2.9 KiB — 4 ms — h2https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/search/search-16.33cf8483a28f.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/search/search-16.33cf8483a28f.svg — 200 — 641 B — 7 ms — h2https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/profile/palette-16.028234691e78.svgwww.firefox.com/media/img/firefox/f... https://www.firefox.com/media/img/firefox/flare/2026/icons/desktop-16/profile/palette-16.028234691e78.svg — 200 — 1.3 KiB — 4 ms — h2https://www.firefox.com/media/cms/images/Shield_41DIZ0q.width-400.svgwww.firefox.com/media/cms/images/Sh... https://www.firefox.com/media/cms/images/Shield_41DIZ0q.width-400.svg — 200 — 2.1 KiB — 7 ms — h2https://www.firefox.com/media/cms/images/Cursor_HIkIYqM.width-400.svgwww.firefox.com/media/cms/images/Cu... https://www.firefox.com/media/cms/images/Cursor_HIkIYqM.width-400.svg — 200 — 1.4 KiB — 11 ms — h2https://www.firefox.com/media/cms/images/Toggle_DNTkMhH.width-400.svgwww.firefox.com/media/cms/images/To... https://www.firefox.com/media/cms/images/Toggle_DNTkMhH.width-400.svg — 200 — 1.5 KiB — 10 ms — h2https://www.firefox.com/media/cms/images/Bolt_GL1BlXf.width-400.svgwww.firefox.com/media/cms/images/Bo... https://www.firefox.com/media/cms/images/Bolt_GL1BlXf.width-400.svg — 200 — 1.4 KiB — 12 ms — h2https://www.firefox.com/media/fonts/mozilla-headline/MozillaHeadline-Variable.19ade5d17bd1.woff2www.firefox.com/media/fonts/mozilla... https://www.firefox.com/media/fonts/mozilla-headline/MozillaHeadline-Variable.19ade5d17bd1.woff2 — 200 — 68.4 KiB — 21 ms — h2https://www.firefox.com/media/fonts/mozilla-text/MozillaText-Variable.fc7317808d75.woff2www.firefox.com/media/fonts/mozilla... https://www.firefox.com/media/fonts/mozilla-text/MozillaText-Variable.fc7317808d75.woff2 — 200 — 33.0 KiB — 14 ms — h2https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/cm.csstranscend-cdn.com/cm/d556c3a1-e57c-... https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/cm.css — 200 — 4.1 KiB — 19 ms — h3https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/translations/en.jsontranscend-cdn.com/cm/d556c3a1-e57c-... https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/translations/en.json — 200 — 2.5 KiB — 22 ms — h3https://www.firefox.com/media/img/favicons/firefox/browser/favicon.f093404c0135.icowww.firefox.com/media/img/favicons/... https://www.firefox.com/media/img/favicons/firefox/browser/favicon.f093404c0135.ico — 200 — 8.3 KiB — 6 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 698ms · 114KB · €8/mo
www.firefox.com
Other
Costly
Execution 402ms
Transfer 15 KB
Monthly Cost €4/mo
Unattributable
Other
Optional
Execution 179ms
Transfer 0 KB
Monthly Cost €2/mo
transcend-cdn.com
Other
Optional
Execution 117ms
Transfer 99 KB
Unused 46%
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • www.firefox.com adds 402ms and costs ~€4/month

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

www.firefox.com takes 402ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

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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