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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
88
GRADE
B
FIX
1
REVIEW
3
PASS
11
INFO
2

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

Mobile Desktop
60
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.

3.16 s

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

3.34 s

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

158 ms

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

0.948

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

3.16 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.

4.64 s

Page Load Progression

458 ms
916 ms
1.4 s
1.8 s
2.3 s
2.7 s
3.2 s
3.7 s
Checks
17
11 PASS 3 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 (469.6 KiB of 469.8 KiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
B
Image Optimization
22 images, 0 KB saveable
REVIEW
22 images, 0 KB saveable
Info::
All images are well-optimized
22 images 114 KB
0 oversized -0 KB
21 legacy format
0 missing dimensions CLS risk
C
JS Execution Cost
Action
1315ms total JS execution
REVIEW
1315ms total JS execution
Warning::
https://www.mozilla.org/en-US/: 464ms CPU time
Warning::
Unattributable: 346ms CPU time
Warning::
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a4...: 297ms CPU time
Info::
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a4...: 122ms CPU time
Info::
https://www.mozilla.org/media/js/lib.c244ff81b28a....: 86ms CPU time
Warning::
Third-party scripts: 1315ms (100% of total)

Main Thread Breakdown

Other 32% Script Evaluation 29% Style & Layout 24% Script Parsing & Compilation 6% Rendering 5% Parse HTML & CSS 3%
ScriptTotalScriptingParse/CompileParty
https://www.mozilla.org/en-US/464ms9ms1ms3rd
Unattributable346ms17ms0ms3rd
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/ui.js297ms230ms42ms3rd
https://transcend-cdn.com/cm/d556c3a1-e57c-4bdf-a490-390a1aebf6dd/airgap.js122ms91ms15ms3rd
https://www.mozilla.org/media/js/lib.c244ff81b28a.js86ms11ms2ms3rd
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
470 KB transferred, 50 requests
PASS
470 KB transferred, 50 requests
Info::
Page weighs 1.1 MB (470 KB transferred)
Info::
50 HTTP requests
Info::
Estimated 0.10 g CO2 per page load
470 KB / 2.4 MB budget
470 KB transferred
50 requests
0.10 g CO2 per page load
JavaScript 197.4 KiB 42%
Images 114.2 KiB 24%
Fonts 107.2 KiB 23%
CSS 25.6 KiB 5%
HTML 21.4 KiB 5%
Other 2.4 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+
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 1.0 s 2.0 s 3.0 s FCP 3.2 s LCP 3.3 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 — 26.2 KiB — 7 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 — 28.5 KiB — 14 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 — 13 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 — 14 ms — font-display: swap
MozillaText-SemiBold.b1... woff2 swap
Size 26 KB
Load time 7 ms
Start 965 ms
Risk FOUT — text flashes from fallback to web font
MozillaHeadline-SemiBol... woff2 swap
Size 29 KB
Load time 14 ms
Start 966 ms
Risk FOUT — text flashes from fallback to web font
MozillaText-Regular.71c... woff2 swap
Size 26 KB
Load time 13 ms
Start 966 ms
Risk FOUT — text flashes from fallback to web font
MozillaText-Bold.4af7ce... woff2 swap
Size 26 KB
Load time 14 ms
Start 966 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
50 resources · 470 KB · 73 KB savings available
PASS
50 resources · 470 KB · 73 KB savings available
Info::
Within 1MB page-weight target
Got: 470 KB
Info::
~73 KB of savings available
Warning::
49 third-party resources (100% of weight)
50 resources · 469.8 KiB · 49 third-party Within 1MB page-weight target
JavaScript 42% · 197.4 KiB
Image 25% · 115.3 KiB
Font 23% · 107.2 KiB
CSS 5% · 25.6 KiB
Document 5% · 21.9 KiB
Other 1% · 2.4 KiB

~73.2 KiB of savings available

Remove unused JavaScript: 73.2 KiB
A+
Render-Blocking Resources
No render-blocking resources detected
PASS
No render-blocking resources detected
Info::
No render-blocking resources detected in <head>
A+
Third-Party Resources
No third-party resources detected
PASS
No third-party resources detected
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
50 requests over 1402ms
INFO
0 ms 1.0 s 2.0 s 3.0 s FCP 3.2 s LCP 3.3 shttps://mozilla.org// https://mozilla.org/ — 301 — 165 B — 200 ms — h2https://www.mozilla.org/www.mozilla.org/ https://www.mozilla.org/ — 302 — 384 B — 198 ms — h2https://www.mozilla.org/en-US/www.mozilla.org/en-US/ https://www.mozilla.org/en-US/ — 200 — 21.4 KiB — 297 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 — 137 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 — 2.4 KiB — 17 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 — 9.4 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 — 16 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 — 892 B — 16 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 — 20 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 — 21 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 — 19 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 — 2.2 KiB — 18 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 — 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 — 2.6 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 — 2.9 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 — 4 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 — 3 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 — 669 B — 162 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 — 2.3 KiB — 2 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 — 1.1 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 — 1.5 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 — 98.6 KiB — 97 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 — 4 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 — 653 B — 11 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 — 5 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 — 934 B — 7 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 — 7 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 — 11 ms — h2
0 ms 1.0 s 2.0 s 3.0 s FCP 3.2 s LCP 3.3 shttps://mozilla.org// https://mozilla.org/ — 301 — 165 B — 200 ms — h2https://www.mozilla.org/www.mozilla.org/ https://www.mozilla.org/ — 302 — 384 B — 198 ms — h2https://www.mozilla.org/en-US/www.mozilla.org/en-US/ https://www.mozilla.org/en-US/ — 200 — 21.4 KiB — 297 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 — 137 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 — 2.4 KiB — 17 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 — 9.4 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 — 16 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 — 892 B — 16 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 — 20 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 — 21 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 — 19 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 — 2.2 KiB — 18 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 — 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 — 2.6 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 — 2.9 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 — 4 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 — 3 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 — 669 B — 162 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 — 2.3 KiB — 2 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 — 1.1 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 — 1.5 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 — 98.6 KiB — 97 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 — 4 ms — 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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 1315ms · 178KB · €14/mo
www.mozilla.org
Other
Costly
Execution 464ms
Transfer 21 KB
Monthly Cost €5/mo
Unattributable
Other
Costly
Execution 346ms
Transfer 0 KB
Monthly Cost €4/mo
transcend-cdn.com
Other
Costly
Execution 297ms
Transfer 99 KB
Unused 46%
Monthly Cost €3/mo
transcend-cdn.com
Other
Optional
Execution 122ms
Transfer 52 KB
Unused 54%
Monthly Cost €1/mo
www.mozilla.org
Other
Optional
Execution 86ms
Transfer 6 KB
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • www.mozilla.org adds 464ms and costs ~€5/month
  • Unattributable adds 346ms and costs ~€4/month
  • transcend-cdn.com adds 297ms and costs ~€3/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.mozilla.org takes 464ms 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

Unattributable takes 346ms 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

transcend-cdn.com takes 297ms 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

54% of transcend-cdn.com's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

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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