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https://thunderbird.net

Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
74
GRADE
C
FIX
3
REVIEW
2
PASS
8
INFO
2

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

Mobile Desktop
92
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
92
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
81
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.

858 ms

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

1.72 s

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

2 ms

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

0.010

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

919 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.

2.47 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 2 REVIEW 3 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 (1.9 MiB of 1.9 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
JS Bundles
Action
16 scripts, 661 KB unused
FIX
16 scripts, 661 KB unused
Warning::
https://static.fundraiseup.com/checkout.9e2624d0be...: 366 KB unused (89%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://static.fundraiseup.com/checkout-sentry-ven...: 112 KB unused (100%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://static.fundraiseup.com/checkout-vendors.78...: 87 KB unused (83%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.thunderbird.net/media/js/common-bundle...: 30 KB unused (60%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.thunderbird.net/media/js/common-bundle...: unminified — 12 KB could be saved
Warning::
https://static.fundraiseup.com/checkout-styles.fab...: 22 KB unused (100%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 661 KB
661 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://static.fundraiseup.com/checkout.9e2624d0be733d7f.js410 KB366 KB (89%)✓3rd
https://static.fundraiseup.com/checkout-sentry-vendor.dda4c7629502a974.js112 KB112 KB (100%)✓3rd
https://static.fundraiseup.com/checkout-vendors.78ab7844d94042df.js105 KB87 KB (83%)✓3rd
https://www.thunderbird.net/media/js/common-bundle.js50 KB30 KB (60%)✗3rd
https://static.fundraiseup.com/checkout-styles.fab72e48733dfd10.js23 KB22 KB (100%)✓3rd
https://www.thunderbird.net/media/js/matomo.js36 KB22 KB (63%)✓3rd
https://cdn.fundraiseup.com/widget/ADGJGYAN65 KB22 KB (34%)✓3rd
https://static.fundraiseup.com/elements-langs-vendors.86315bee0669542d.js140 KB—✓3rd
https://static.fundraiseup.com/elements-vendors.c590dd34e4f5ac29.js21 KB—✓3rd
https://cdn.fundraiseup.com/embed-data/elements-global/ADGJGYAN.js0 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

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

F
Page Weight Inventory
Action
53 resources · 1.9 MB · 661 KB savings available
FIX
53 resources · 1.9 MB · 661 KB savings available
Warning::
Page weight 919 KB over 1MB target
Got: 1.9 MB Expected: ≤ 1 MB
Info::
~661 KB of savings available
Warning::
52 third-party resources (100% of weight)
Info::
2 resources over 200KB
53 resources · 1.9 MiB · 52 third-party 918.6 KiB over 1MB target
JavaScript 52% · 1017.5 KiB
Image 25% · 490.4 KiB
Font 19% · 375.7 KiB
Document 2% · 39.2 KiB
CSS 1% · 18.8 KiB
Other 0% · 1.1 KiB

~660.6 KiB of savings available

Remove unused JavaScript: 660.6 KiB
C
Page Weight Budget
Action
1.9 MB transferred, 53 requests
REVIEW
1.9 MB transferred, 53 requests
Info::
Page weighs 5.4 MB (1.9 MB transferred)
Warning::
JavaScript is 1018 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1018 KB
Info::
Fonts are 376 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 376 KB
Info::
53 HTTP requests
Info::
Estimated 0.40 g CO2 per page load
1.9 MB / 2.4 MB budget
1.9 MB transferred
53 requests
0.40 g CO2 per page load
JavaScript 1017.5 KiB 52%
Images 482.2 KiB 25%
Fonts 375.7 KiB 19%
HTML 38.7 KiB 2%
CSS 18.8 KiB 1%
Other 8.7 KiB 0%
Other 967 B 0%
Other 149 B 0%
0 2.4 MB 4.9 MB
Approaching limit

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

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

B
Image Optimization
24 images, 0 KB saveable
REVIEW
24 images, 0 KB saveable
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.thunderbird.net/media/img/thunderbird/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
24 images 482 KB
0 oversized -0 KB
2 legacy format
14 missing dimensions CLS risk

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

Set explicit width and height to prevent CLS.

Why this matters

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

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
439ms total JS execution
PASS
439ms total JS execution
Warning::
https://www.thunderbird.net/en-US/: 296ms CPU time
Info::
Unattributable: 87ms CPU time
Info::
https://static.fundraiseup.com/checkout-vendors.78...: 55ms CPU time
Warning::
Third-party scripts: 439ms (100% of total)

Main Thread Breakdown

Style & Layout 31% Script Evaluation 27% Other 23% Script Parsing & Compilation 15% Rendering 3%
ScriptTotalScriptingParse/CompileParty
https://www.thunderbird.net/en-US/296ms3ms1ms3rd
Unattributable87ms6ms0ms3rd
https://static.fundraiseup.com/checkout-vendors.78ab7844d94042df.js55ms48ms7ms3rd
A+
Font Loading
4 fonts (376 KB)
PASS
4 fonts (376 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

376 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 858 ms LCP 1.7 shttps://www.thunderbird.net/media/fonts/Inter/Inter-roman.var.woff2?v=3.19Inter-roman.var.woff2 https://www.thunderbird.net/media/fonts/Inter/Inter-roman.var.woff2?v=3.19 — 222.1 KiB — 113 ms — font-display: swaphttps://www.thunderbird.net/media/fonts/Metropolis/Metropolis-Medium.woff2Metropolis-Medium.woff2 https://www.thunderbird.net/media/fonts/Metropolis/Metropolis-Medium.woff2 — 26.0 KiB — 109 ms — font-display: swaphttps://www.thunderbird.net/media/fonts/Metropolis/Metropolis-Regular.woff2Metropolis-Regular.woff2 https://www.thunderbird.net/media/fonts/Metropolis/Metropolis-Regular.woff2 — 23.8 KiB — 24 ms — font-display: swaphttps://www.thunderbird.net/media/fonts/Inter/Inter-Medium.woff2?v=3.19Inter-Medium.woff2 https://www.thunderbird.net/media/fonts/Inter/Inter-Medium.woff2?v=3.19 — 103.7 KiB — 112 ms — font-display: swap
Inter-roman.var.woff2 woff2 swap
Size 222 KB
Load time 113 ms
Start 426 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
Metropolis-Medium.woff2 woff2 swap
Size 26 KB
Load time 109 ms
Start 426 ms
Risk FOUT — text flashes from fallback to web font
Metropolis-Regular.woff2 woff2 swap
Size 24 KB
Load time 24 ms
Start 427 ms
Risk FOUT — text flashes from fallback to web font
Inter-Medium.woff2 woff2 swap
Size 104 KB
Load time 112 ms
Start 427 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
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)

Fixing the unchecked items could save ~163 KB and ~326 ms

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: Cloudflare

A
HTTP Caching
max-age=21600 (6 hours)
PASS
max-age=21600 (6 hours)
Info::
Cache-Control header is set
Got: max-age=21600
Info::
Effective TTL: 6 hours (max-age=21600)
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

max-age=21600

DirectiveValueMeaning
max-age21600Cache for 6 hours
Effective TTL: 21600 seconds
Network Waterfall
53 requests over 1819ms
INFO
0 ms 500 ms 1.0 s 1.5 s FCP 858 ms LCP 1.7 shttps://thunderbird.net// https://thunderbird.net/ — 302 — 263 B — 44 ms — h3https://www.thunderbird.net/www.thunderbird.net/ https://www.thunderbird.net/ — 302 — 253 B — 191 ms — h3https://www.thunderbird.net/en-US/www.thunderbird.net/en-US/ https://www.thunderbird.net/en-US/ — 200 — 38.7 KiB — 90 ms — h3https://www.thunderbird.net/media/js/site-bundle.jswww.thunderbird.net/media/js/site-b... https://www.thunderbird.net/media/js/site-bundle.js — 200 — 6.0 KiB — 43 ms — h3https://www.thunderbird.net/media/js/common-bundle.jswww.thunderbird.net/media/js/common... https://www.thunderbird.net/media/js/common-bundle.js — 200 — 50.2 KiB — 72 ms — h3https://www.thunderbird.net/media/css/normalize.csswww.thunderbird.net/media/css/norma... https://www.thunderbird.net/media/css/normalize.css — 200 — 2.0 KiB — 29 ms — h3https://www.thunderbird.net/media/css/base-style.csswww.thunderbird.net/media/css/base-... https://www.thunderbird.net/media/css/base-style.css — 200 — 16.8 KiB — 56 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/competitors/floating-icon-apple.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/competitors/floating-icon-apple.avif — 200 — 3.4 KiB — 34 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/competitors/floating-icon-gmail.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/competitors/floating-icon-gmail.avif — 200 — 3.6 KiB — 34 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/competitors/floating-icon-outlook.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/competitors/floating-icon-outlook.avif — 200 — 3.8 KiB — 25 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/competitors/floating-icon-proton.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/competitors/floating-icon-proton.avif — 200 — 3.2 KiB — 26 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/competitors/floating-icon-yahoo.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/competitors/floating-icon-yahoo.avif — 200 — 3.5 KiB — 39 ms — h3https://www.thunderbird.net/media/js/matomo-config.jswww.thunderbird.net/media/js/matomo... https://www.thunderbird.net/media/js/matomo-config.js — 200 — 585 B — 34 ms — h3https://www.thunderbird.net/media/img/l10n/en-US/thunderbird/base/home/banner-high-res.avifwww.thunderbird.net/media/img/l10n/... https://www.thunderbird.net/media/img/l10n/en-US/thunderbird/base/home/banner-high-res.avif — 200 — 75.4 KiB — 66 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/screens/laptop-bg.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/screens/laptop-bg.avif — 200 — 10.7 KiB — 38 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/screens/mail-screen.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/screens/mail-screen.avif — 200 — 128.1 KiB — 74 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/screens/calendar-screen.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/screens/calendar-screen.avif — 200 — 38.0 KiB — 67 ms — h3https://www.thunderbird.net/media/img/thunderbird/base/home/flat-phone-high-res.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/base/home/flat-phone-high-res.avif — 200 — 11.9 KiB — 60 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/planets/planets-firefox.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/planets/planets-firefox.avif — 200 — 6.4 KiB — 37 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/planets/planets-thunderbird.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/planets/planets-thunderbird.avif — 200 — 19.5 KiB — 65 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-max.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-max.avif — 200 — 8.5 KiB — 59 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/unified-inbox.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/unified-inbox.avif — 200 — 11.1 KiB — 60 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-juan.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-juan.avif — 200 — 6.8 KiB — 59 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-ernie.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-ernie.avif — 200 — 3.7 KiB — 59 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-rolando.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-rolando.avif — 200 — 8.2 KiB — 59 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-beegy.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-beegy.avif — 200 — 2.4 KiB — 51 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-dom.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-dom.avif — 200 — 5.3 KiB — 55 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/hex.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/hex.avif — 200 — 69.9 KiB — 69 ms — h3https://www.thunderbird.net/media/img/thunderbird/base/home/exploding-phone-high-res.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/base/home/exploding-phone-high-res.avif — 200 — 48.1 KiB — 67 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/phone/cta-phone.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/phone/cta-phone.avif — 200 — 9.3 KiB — 60 ms — h3
0 ms 500 ms 1.0 s 1.5 s FCP 858 ms LCP 1.7 shttps://thunderbird.net// https://thunderbird.net/ — 302 — 263 B — 44 ms — h3https://www.thunderbird.net/www.thunderbird.net/ https://www.thunderbird.net/ — 302 — 253 B — 191 ms — h3https://www.thunderbird.net/en-US/www.thunderbird.net/en-US/ https://www.thunderbird.net/en-US/ — 200 — 38.7 KiB — 90 ms — h3https://www.thunderbird.net/media/js/site-bundle.jswww.thunderbird.net/media/js/site-b... https://www.thunderbird.net/media/js/site-bundle.js — 200 — 6.0 KiB — 43 ms — h3https://www.thunderbird.net/media/js/common-bundle.jswww.thunderbird.net/media/js/common... https://www.thunderbird.net/media/js/common-bundle.js — 200 — 50.2 KiB — 72 ms — h3https://www.thunderbird.net/media/css/normalize.csswww.thunderbird.net/media/css/norma... https://www.thunderbird.net/media/css/normalize.css — 200 — 2.0 KiB — 29 ms — h3https://www.thunderbird.net/media/css/base-style.csswww.thunderbird.net/media/css/base-... 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h3https://www.thunderbird.net/media/img/thunderbird/new/planets/planets-thunderbird.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/planets/planets-thunderbird.avif — 200 — 19.5 KiB — 65 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-max.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-max.avif — 200 — 8.5 KiB — 59 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/unified-inbox.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/unified-inbox.avif — 200 — 11.1 KiB — 60 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-juan.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-juan.avif — 200 — 6.8 KiB — 59 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-ernie.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-ernie.avif — 200 — 3.7 KiB — 59 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-rolando.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-rolando.avif — 200 — 8.2 KiB — 59 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-beegy.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-beegy.avif — 200 — 2.4 KiB — 51 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-dom.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/testimonial-portrait-dom.avif — 200 — 5.3 KiB — 55 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/testimonials/hex.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/testimonials/hex.avif — 200 — 69.9 KiB — 69 ms — h3https://www.thunderbird.net/media/img/thunderbird/base/home/exploding-phone-high-res.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/base/home/exploding-phone-high-res.avif — 200 — 48.1 KiB — 67 ms — h3https://www.thunderbird.net/media/img/thunderbird/new/phone/cta-phone.avifwww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/new/phone/cta-phone.avif — 200 — 9.3 KiB — 60 ms — h3https://www.thunderbird.net/media/js/matomo.jswww.thunderbird.net/media/js/matomo... https://www.thunderbird.net/media/js/matomo.js — 200 — 35.6 KiB — 67 ms — h3https://cdn.fundraiseup.com/widget/ADGJGYANcdn.fundraiseup.com/widget/ADGJGYAN https://cdn.fundraiseup.com/widget/ADGJGYAN — 200 — 65.1 KiB — 105 ms — h2https://www.thunderbird.net/media/svg/chevron-right.svgwww.thunderbird.net/media/svg/chevr... https://www.thunderbird.net/media/svg/chevron-right.svg — 200 — 752 B — 48 ms — h3https://www.thunderbird.net/media/svg/chevron-down.svgwww.thunderbird.net/media/svg/chevr... https://www.thunderbird.net/media/svg/chevron-down.svg — 200 — 682 B — 42 ms — h3https://www.thunderbird.net/media/fonts/Inter/Inter-roman.var.woff2?v=3.19www.thunderbird.net/media/fonts/Int... https://www.thunderbird.net/media/fonts/Inter/Inter-roman.var.woff2?v=3.19 — 200 — 222.1 KiB — 113 ms — h3https://www.thunderbird.net/media/fonts/Metropolis/Metropolis-Medium.woff2www.thunderbird.net/media/fonts/Met... https://www.thunderbird.net/media/fonts/Metropolis/Metropolis-Medium.woff2 — 200 — 26.0 KiB — 109 ms — 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h2https://thunderbird.innocraft.cloud/piwik.php?action_name=www.thunderbird.net%2FThunderbird%20%E2%80%94%20Free%20Your%20Inbox.%20%E2%80%94%20Thunderbird&idsite=1&rec=1&r=518314&h=23&m=3&s=49&url=https%3A%2F%2Fwww.thunderbird.net%2Fen-US%2F&_id=&_idn=1&send_image=0&_refts=0&pv_id=ZF4a4R&fa_pv=1&fa_fp[0][fa_vid]=5znf4S&fa_fp[0][fa_id]=mc-embedded-subscribe-form&fa_fp[0][fa_name]=mc-embedded-subscribe-form&fa_fp[0][fa_fv]=1&fa_fp[1][fa_vid]=pcwipe&fa_fp[1][fa_id]=lang_form&fa_fp[1][fa_fv]=1&pf_net=0&pf_srv=28&pf_tfr=62&uadata=%7B%22fullVersionList%22%3A%5B%7B%22brand%22%3A%22Chromium%22%2C%22version%22%3A%22147.0.7727.101%22%7D%2C%7B%22brand%22%3A%22Not.A%2FBrand%22%2C%22version%22%3A%228.0.0.0%22%7D%5D%2C%22mobile%22%3Afalse%2C%22model%22%3A%22%22%2C%22platform%22%3A%22macOS%22%2C%22platformVersion%22%3A%2210.15.7%22%7D&pdf=1&qt=0&realp=0&wma=0&fla=0&java=0&ag=0&cookie=1&res=800x600thunderbird.innocraft.cloud/piwik.p... https://thunderbird.innocraft.cloud/piwik.php?action_name=www.thunderbird.net%2FThunderbird%20%E2%80%94%20Free%20Your%20Inbox.%20%E2%80%94%20Thunderbird&idsite=1&rec=1&r=518314&h=23&m=3&s=49&url=https%3A%2F%2Fwww.thunderbird.net%2Fen-US%2F&_id=&_idn=1&send_image=0&_refts=0&pv_id=ZF4a4R&fa_pv=1&fa_fp[0][fa_vid]=5znf4S&fa_fp[0][fa_id]=mc-embedded-subscribe-form&fa_fp[0][fa_name]=mc-embedded-subscribe-form&fa_fp[0][fa_fv]=1&fa_fp[1][fa_vid]=pcwipe&fa_fp[1][fa_id]=lang_form&fa_fp[1][fa_fv]=1&pf_net=0&pf_srv=28&pf_tfr=62&uadata=%7B%22fullVersionList%22%3A%5B%7B%22brand%22%3A%22Chromium%22%2C%22version%22%3A%22147.0.7727.101%22%7D%2C%7B%22brand%22%3A%22Not.A%2FBrand%22%2C%22version%22%3A%228.0.0.0%22%7D%5D%2C%22mobile%22%3Afalse%2C%22model%22%3A%22%22%2C%22platform%22%3A%22macOS%22%2C%22platformVersion%22%3A%2210.15.7%22%7D&pdf=1&qt=0&realp=0&wma=0&fla=0&java=0&ag=0&cookie=1&res=800x600 — 204 — 149 B — 170 ms — h2https://fndrsp.net/tbfndrsp.net/tb https://fndrsp.net/tb — 200 — 504 B — 158 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 439ms · 144KB · $6/mo
www.thunderbird.net
Other
Costly
Execution 296ms
Transfer 39 KB
Monthly Cost $4/mo
Unattributable
Other
Optional
Execution 87ms
Transfer 0 KB
Monthly Cost $1/mo
static.fundraiseup.com
Other
Optional
Execution 55ms
Transfer 105 KB
Unused 83%
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • www.thunderbird.net adds 296ms 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.thunderbird.net takes 296ms 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

83% of static.fundraiseup.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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