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https://thunderbird.net

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
74
GRADE
C
FIX
4
REVIEW
2
PASS
9
INFO
2

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

Mobile Desktop
44
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.

9.53 s

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

12.39 s

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

468 ms

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

0.002

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

9.53 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.

12.51 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
17
9 PASS 2 REVIEW 4 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
D
JS Execution Cost
Action
2251ms total JS execution
FIX
2251ms total JS execution
Warning::
https://www.thunderbird.net/en-US/: 743ms CPU time
Warning::
https://static.fundraiseup.com/checkout.9e2624d0be...: 492ms CPU time
Warning::
Unattributable: 306ms CPU time
Info::
https://static.fundraiseup.com/link-v2.0cc05dda47c...: 238ms CPU time
Info::
https://cdn.fundraiseup.com/widget/ADGJGYAN: 183ms CPU time
Warning::
Third-party scripts: 2251ms (100% of total)

Main Thread Breakdown

Script Evaluation 36% Other 21% Style & Layout 20% Script Parsing & Compilation 18% Rendering 3%
ScriptTotalScriptingParse/CompileParty
https://www.thunderbird.net/en-US/743ms11ms5ms3rd
https://static.fundraiseup.com/checkout.9e2624d0be733d7f.js492ms315ms176ms3rd
Unattributable306ms15ms0ms3rd
https://static.fundraiseup.com/link-v2.0cc05dda47c51ab7.js238ms165ms4ms3rd
https://cdn.fundraiseup.com/widget/ADGJGYAN183ms153ms21ms3rd
https://static.fundraiseup.com/elementsApi.c0fc24ed4d35f527.js104ms86ms15ms3rd
https://static.fundraiseup.com/elements-langs-vendors.86315bee0669542d.js93ms1ms91ms3rd
https://www.thunderbird.net/media/js/common-bundle.js93ms59ms12ms3rd
F
JS Bundles
Action
16 scripts, 660 KB unused
FIX
16 scripts, 660 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: 660 KB
660 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 · 660 KB savings available
FIX
53 resources · 1.9 MB · 660 KB savings available
Warning::
Page weight 918 KB over 1MB target
Got: 1.9 MB Expected: ≤ 1 MB
Info::
~660 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 918.2 KiB over 1MB target
JavaScript 52% · 1017.2 KiB
Image 25% · 490.4 KiB
Font 19% · 375.7 KiB
Document 2% · 39.0 KiB
CSS 1% · 18.8 KiB
Other 0% · 1.1 KiB

~660.4 KiB of savings available

Remove unused JavaScript: 660.4 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 1017 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1017 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 1017.2 KiB 52%
Images 482.2 KiB 25%
Fonts 375.7 KiB 19%
HTML 38.6 KiB 2%
CSS 18.8 KiB 1%
Other 8.6 KiB 0%
Other 969 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.
24 images 482 KB
0 oversized -0 KB
2 legacy format
11 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

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 (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 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s FCP 9.5 s LCP 12.4 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 — 35 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 — 29 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 — 35 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 — 31 ms — font-display: swap
Inter-roman.var.woff2 woff2 swap
Size 222 KB
Load time 35 ms
Start 492 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 29 ms
Start 493 ms
Risk FOUT — text flashes from fallback to web font
Metropolis-Regular.woff2 woff2 swap
Size 24 KB
Load time 35 ms
Start 493 ms
Risk FOUT — text flashes from fallback to web font
Inter-Medium.woff2 woff2 swap
Size 104 KB
Load time 31 ms
Start 493 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+
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: 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 1734ms
INFO
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s FCP 9.5 s LCP 12.4 shttps://thunderbird.net// https://thunderbird.net/ — 302 — 213 B — 67 ms — h2https://www.thunderbird.net/www.thunderbird.net/ https://www.thunderbird.net/ — 302 — 182 B — 211 ms — h2https://www.thunderbird.net/en-US/www.thunderbird.net/en-US/ https://www.thunderbird.net/en-US/ — 200 — 38.6 KiB — 35 ms — h2https://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 — 40 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 — 91 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 — 25 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 — 70 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 — 60 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 — 64 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 — 26 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 — 27 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 — 26 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 — 28 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 — 79 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 — 31 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 — 81 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 — 69 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 — 58 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 — 57 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 — 58 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 — 57 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 — 58 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 — 57 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 — 57 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 — 58 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 — 52 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 — 57 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 — 75 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 — 69 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 — 57 ms — h3
0 ms 2.0 s 4.0 s 6.0 s 8.0 s 10.0 s 12.0 s FCP 9.5 s LCP 12.4 shttps://thunderbird.net// https://thunderbird.net/ — 302 — 213 B — 67 ms — h2https://www.thunderbird.net/www.thunderbird.net/ https://www.thunderbird.net/ — 302 — 182 B — 211 ms — h2https://www.thunderbird.net/en-US/www.thunderbird.net/en-US/ https://www.thunderbird.net/en-US/ — 200 — 38.6 KiB — 35 ms — h2https://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 — 40 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 — 91 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 — 25 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 — 70 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 — 60 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 — 64 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 — 26 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 — 27 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 — 26 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 — 28 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 — 79 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 — 31 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 — 81 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 — 69 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 — 58 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 — 57 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 — 58 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 — 57 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 — 58 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 — 57 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 — 57 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 — 58 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 — 52 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 — 57 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 — 75 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 — 69 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 — 57 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 — 66 ms — h3https://cdn.fundraiseup.com/widget/ADGJGYANcdn.fundraiseup.com/widget/ADGJGYAN https://cdn.fundraiseup.com/widget/ADGJGYAN — 200 — 65.1 KiB — 148 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 — 43 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 — 37 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 — 35 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 — 29 ms — h3https://www.thunderbird.net/media/fonts/Metropolis/Metropolis-Regular.woff2www.thunderbird.net/media/fonts/Met... https://www.thunderbird.net/media/fonts/Metropolis/Metropolis-Regular.woff2 — 200 — 23.8 KiB — 35 ms — h3https://www.thunderbird.net/media/fonts/Inter/Inter-Medium.woff2?v=3.19www.thunderbird.net/media/fonts/Int... https://www.thunderbird.net/media/fonts/Inter/Inter-Medium.woff2?v=3.19 — 200 — 103.7 KiB — 31 ms — h3https://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=597524&h=23&m=3&s=31&url=https%3A%2F%2Fwww.thunderbird.net%2Fen-US%2F&_id=&_idn=1&send_image=0&_refts=0&pv_id=fm2ygZ&fa_pv=1&fa_fp[0][fa_vid]=mH280J&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]=10XMiH&fa_fp[1][fa_id]=lang_form&fa_fp[1][fa_fv]=1&pf_net=0&pf_srv=29&pf_tfr=5&pf_dm1=201&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%3Atrue%2C%22model%22%3A%22moto%20g%20power%20(2022)%22%2C%22platform%22%3A%22Android%22%2C%22platformVersion%22%3A%2211.0%22%7D&pdf=1&qt=0&realp=0&wma=0&fla=0&java=0&ag=0&cookie=1&res=412x823thunderbird.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=597524&h=23&m=3&s=31&url=https%3A%2F%2Fwww.thunderbird.net%2Fen-US%2F&_id=&_idn=1&send_image=0&_refts=0&pv_id=fm2ygZ&fa_pv=1&fa_fp[0][fa_vid]=mH280J&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]=10XMiH&fa_fp[1][fa_id]=lang_form&fa_fp[1][fa_fv]=1&pf_net=0&pf_srv=29&pf_tfr=5&pf_dm1=201&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%3Atrue%2C%22model%22%3A%22moto%20g%20power%20(2022)%22%2C%22platform%22%3A%22Android%22%2C%22platformVersion%22%3A%2211.0%22%7D&pdf=1&qt=0&realp=0&wma=0&fla=0&java=0&ag=0&cookie=1&res=412x823 — 204 — 149 B — 215 ms — h2https://static.fundraiseup.com/elementsApi.c0fc24ed4d35f527.jsstatic.fundraiseup.com/elementsApi.... https://static.fundraiseup.com/elementsApi.c0fc24ed4d35f527.js — 200 — 36.8 KiB — 80 ms — h2https://cdn.fundraiseup.com/embed-data/elements-global/ADGJGYAN.jscdn.fundraiseup.com/embed-data/elem... https://cdn.fundraiseup.com/embed-data/elements-global/ADGJGYAN.js — 200 — 152 B — 29 ms — h2https://static.fundraiseup.com/elements-langs-vendors.86315bee0669542d.jsstatic.fundraiseup.com/elements-lan... https://static.fundraiseup.com/elements-langs-vendors.86315bee0669542d.js — 200 — 139.6 KiB — 104 ms — h2https://static.fundraiseup.com/elements-vendors.c590dd34e4f5ac29.jsstatic.fundraiseup.com/elements-ven... https://static.fundraiseup.com/elements-vendors.c590dd34e4f5ac29.js — 200 — 21.4 KiB — 64 ms — h2https://static.fundraiseup.com/checkout.9e2624d0be733d7f.jsstatic.fundraiseup.com/checkout.9e2... https://static.fundraiseup.com/checkout.9e2624d0be733d7f.js — 200 — 410.1 KiB — 130 ms — h2https://static.fundraiseup.com/checkout-vendors.78ab7844d94042df.jsstatic.fundraiseup.com/checkout-ven... https://static.fundraiseup.com/checkout-vendors.78ab7844d94042df.js — 200 — 105.4 KiB — 95 ms — h2https://static.fundraiseup.com/checkout-styles.fab72e48733dfd10.jsstatic.fundraiseup.com/checkout-sty... https://static.fundraiseup.com/checkout-styles.fab72e48733dfd10.js — 200 — 22.6 KiB — 62 ms — h2https://static.fundraiseup.com/checkout-sentry-vendor.dda4c7629502a974.jsstatic.fundraiseup.com/checkout-sen... https://static.fundraiseup.com/checkout-sentry-vendor.dda4c7629502a974.js — 200 — 111.8 KiB — 107 ms — h2https://fndrsp.net/tbfndrsp.net/tb https://fndrsp.net/tb — 200 — 501 B — 161 ms — h3https://static.fundraiseup.com/7449.d9966e86b20cdf9f.jsstatic.fundraiseup.com/7449.d9966e8... https://static.fundraiseup.com/7449.d9966e86b20cdf9f.js — 200 — 7.0 KiB — 32 ms — h2https://static.fundraiseup.com/9483.5049a274cd651063.jsstatic.fundraiseup.com/9483.5049a27... https://static.fundraiseup.com/9483.5049a274cd651063.js — 200 — 3.9 KiB — 34 ms — h2https://static.fundraiseup.com/link-v2.0cc05dda47c51ab7.jsstatic.fundraiseup.com/link-v2.0cc0... https://static.fundraiseup.com/link-v2.0cc05dda47c51ab7.js — 200 — 1.1 KiB — 36 ms — h2https://www.thunderbird.net/media/img/thunderbird/favicon.icowww.thunderbird.net/media/img/thund... https://www.thunderbird.net/media/img/thunderbird/favicon.ico — 200 — 8.2 KiB — 26 ms — h3https://fndrsp.net/tbfndrsp.net/tb https://fndrsp.net/tb — 200 — 468 B — 111 ms — h3
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 2251ms · 741KB · $30/mo
www.thunderbird.net
Other
Costly
Execution 743ms
Transfer 39 KB
Monthly Cost $10/mo
static.fundraiseup.com
Other
Costly
Execution 492ms
Transfer 410 KB
Unused 89%
Monthly Cost $7/mo
Unattributable
Other
Costly
Execution 306ms
Transfer 0 KB
Monthly Cost $4/mo
static.fundraiseup.com
Other
Costly
Execution 238ms
Transfer 1 KB
Monthly Cost $3/mo
cdn.fundraiseup.com
Other
Optional
Execution 183ms
Transfer 65 KB
Unused 34%
Monthly Cost $2/mo
static.fundraiseup.com
Other
Optional
Execution 104ms
Transfer 37 KB
Monthly Cost $1/mo
static.fundraiseup.com
Other
Optional
Execution 93ms
Transfer 140 KB
Monthly Cost $1/mo
www.thunderbird.net
Other
Optional
Execution 93ms
Transfer 50 KB
Unused 60%
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • www.thunderbird.net adds 743ms and costs ~$10/month
  • static.fundraiseup.com adds 492ms and costs ~$7/month
  • Unattributable adds 306ms and costs ~$4/month
  • static.fundraiseup.com adds 238ms 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.thunderbird.net takes 743ms 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

static.fundraiseup.com takes 492ms 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

89% 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

Unattributable takes 306ms 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

static.fundraiseup.com takes 238ms 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

60% of www.thunderbird.net'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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