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https://worldwildlife.org

Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
86
GRADE
B
FIX
2
REVIEW
1
PASS
10
INFO
2

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

Mobile Desktop
72
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
99
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
92
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.

836 ms

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

1.37 s

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

0 ms

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

0.680

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

836 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.

1.38 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
10 PASS 1 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 (917.2 KiB of 917.3 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
JS Bundles
5 scripts, 130 KB unused
REVIEW
5 scripts, 130 KB unused
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-PTT...: 85 KB unused (48%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.worldwildlife.org/static/js/main.08aab...: 45 KB unused (86%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 130 KB
130 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtm.js?id=GTM-PTTJ3C2M177 KB85 KB (48%)✓3rd
https://www.worldwildlife.org/static/js/main.08aab79dcfc6.js53 KB45 KB (86%)✓3rd
https://cdn.cookielaw.org/scripttemplates/otSDKStub.js0 KB—✓3rd
https://assets.worldwildlife.org/www-prd/misc/OneTrust/OtAutoBlock.js4 KB—✓3rd
https://challenges.cloudflare.com/turnstile/v0/b/0b8fb825cb67/api.js17 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
917 KB transferred, 21 requests
PASS
917 KB transferred, 21 requests
Info::
Page weighs 1.7 MB (917 KB transferred)
Info::
Fonts are 273 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 273 KB
Info::
21 HTTP requests
Info::
Estimated 0.19 g CO2 per page load
917 KB / 2.4 MB budget
917 KB transferred
21 requests
0.19 g CO2 per page load
Images 323.0 KiB 35%
Fonts 273.3 KiB 30%
JavaScript 251.7 KiB 27%
CSS 31.9 KiB 3%
HTML 26.0 KiB 3%
Other 9.2 KiB 1%
Other 2.2 KiB 0%
0 2.4 MB 4.9 MB
Under budget

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

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+
Image Optimization
8 images, 0 KB saveable
PASS
8 images, 0 KB saveable
Info::
All images are well-optimized
8 images 323 KB
0 oversized -0 KB
1 legacy format
0 missing dimensions CLS risk
A+
JS Execution Cost
255ms total JS execution
PASS
255ms total JS execution
Info::
https://www.worldwildlife.org/: 137ms CPU time
Info::
Unattributable: 62ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-PTT...: 56ms CPU time
Warning::
Third-party scripts: 255ms (100% of total)

Main Thread Breakdown

Other 31% Style & Layout 27% Script Evaluation 21% Rendering 6% Script Parsing & Compilation 6% Parse HTML & CSS 6%
ScriptTotalScriptingParse/CompileParty
https://www.worldwildlife.org/137ms3ms1ms3rd
Unattributable62ms2ms0ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-PTTJ3C2M56ms37ms10ms3rd
A+
Font Loading
1 fonts (273 KB)
PASS
1 fonts (273 KB)
Info::
1 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

1

273 KB total

Render-blocking

0

of 1

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 836 ms LCP 1.4 shttps://www.worldwildlife.org/static/fonts/OpenSans-VariableFont.65c46fe9fcc0.woff2OpenSans-VariableFont.6... https://www.worldwildlife.org/static/fonts/OpenSans-VariableFont.65c46fe9fcc0.woff2 — 273.3 KiB — 62 ms — font-display: swap
OpenSans-VariableFont.6... woff2 swap
Size 273 KB
Load time 62 ms
Start 257 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 ~137 KB and ~274 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
Page Weight Inventory
21 resources · 917 KB · 130 KB savings available
PASS
21 resources · 917 KB · 130 KB savings available
Info::
Within 1MB page-weight target
Got: 917 KB
Info::
~130 KB of savings available
Warning::
20 third-party resources (100% of weight)
Info::
1 resources over 200KB
21 resources · 917.3 KiB · 20 third-party Within 1MB page-weight target
Image 35% · 324.8 KiB
Font 30% · 273.3 KiB
JavaScript 27% · 251.7 KiB
Document 4% · 35.2 KiB
CSS 3% · 31.9 KiB
Other 0% · 444 B

~130.3 KiB of savings available

Remove unused JavaScript: 130.3 KiB
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Cloudflare

Network Waterfall
21 requests over 522ms
INFO
0 ms 500 ms 1.0 s FCP 836 ms LCP 1.4 shttps://worldwildlife.org// https://worldwildlife.org/ — 301 — 179 B — 60 ms — h3https://www.worldwildlife.org/www.worldwildlife.org/ https://www.worldwildlife.org/ — 200 — 26.0 KiB — 98 ms — h3https://cdn.cookielaw.org/scripttemplates/otSDKStub.jscdn.cookielaw.org/scripttemplates/o... https://cdn.cookielaw.org/scripttemplates/otSDKStub.js — -1 — 0 B — 68 ms — https://assets.worldwildlife.org/www-prd/misc/OneTrust/OtAutoBlock.jsassets.worldwildlife.org/www-prd/mi... https://assets.worldwildlife.org/www-prd/misc/OneTrust/OtAutoBlock.js — 200 — 4.5 KiB — 37 ms — h3https://www.worldwildlife.org/static/css/main.eba748cdc84a.csswww.worldwildlife.org/static/css/ma... https://www.worldwildlife.org/static/css/main.eba748cdc84a.css — 200 — 31.9 KiB — 58 ms — h3https://assets.worldwildlife.org/www-prd/images/shutterstock_2325484.b686c5e0.fill-1440x560.format-webp.webpassets.worldwildlife.org/www-prd/im... https://assets.worldwildlife.org/www-prd/images/shutterstock_2325484.b686c5e0.fill-1440x560.format-webp.webp — 200 — 101.5 KiB — 67 ms — h3https://www.worldwildlife.org/static/js/main.08aab79dcfc6.jswww.worldwildlife.org/static/js/mai... https://www.worldwildlife.org/static/js/main.08aab79dcfc6.js — 200 — 53.0 KiB — 80 ms — h3https://challenges.cloudflare.com/turnstile/v0/api.js?render=explicitchallenges.cloudflare.com/turnstile... https://challenges.cloudflare.com/turnstile/v0/api.js?render=explicit — 302 — 265 B — 42 ms — h3https://www.googletagmanager.com/gtm.js?id=GTM-PTTJ3C2Mwww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-PTTJ3C2M — 200 — 176.9 KiB — 154 ms — h2https://www.worldwildlife.org/static/fonts/OpenSans-VariableFont.65c46fe9fcc0.woff2www.worldwildlife.org/static/fonts/... https://www.worldwildlife.org/static/fonts/OpenSans-VariableFont.65c46fe9fcc0.woff2 — 200 — 273.3 KiB — 62 ms — h3https://www.worldwildlife.org/site.webmanifestwww.worldwildlife.org/site.webmanif... https://www.worldwildlife.org/site.webmanifest — 403 — 4.6 KiB — 57 ms — h3https://challenges.cloudflare.com/turnstile/v0/b/0b8fb825cb67/api.jschallenges.cloudflare.com/turnstile... https://challenges.cloudflare.com/turnstile/v0/b/0b8fb825cb67/api.js — 200 — 17.3 KiB — 42 ms — h3data:image/svg+xml;utf8,<svg xmlns=%27http://www.w3.org/2000/svg%27 viewBox=%270 0 14 14%27 fill=%2…www.w3.org/2000/svg%27 viewBox=%270... data:image/svg+xml;utf8,<svg xmlns=%27http://www.w3.org/2000/svg%27 viewBox=%270 0 14 14%27 fill=%2… — 200 — 0 B — 0 ms — datahttps://www.worldwildlife.org/static/images/cssBackgrounds/panda.4c41703e5fd3.svgwww.worldwildlife.org/static/images... https://www.worldwildlife.org/static/images/cssBackgrounds/panda.4c41703e5fd3.svg — 200 — 2.2 KiB — 48 ms — h3https://assets.worldwildlife.org/www-prd/images/Medium_WW239231.2e16d0ba.fill-672x504.format-webp.webpassets.worldwildlife.org/www-prd/im... https://assets.worldwildlife.org/www-prd/images/Medium_WW239231.2e16d0ba.fill-672x504.format-webp.webp — 200 — 35.8 KiB — 32 ms — h3https://assets.worldwildlife.org/www-prd/images/_Bella_Roscher___WWF-.2e16d0ba.fill-400x300.format-webp.webpassets.worldwildlife.org/www-prd/im... https://assets.worldwildlife.org/www-prd/images/_Bella_Roscher___WWF-.2e16d0ba.fill-400x300.format-webp.webp — 200 — 35.4 KiB — 31 ms — h3https://assets.worldwildlife.org/www-prd/images/farm-plowed-WWspring2.2e16d0ba.fill-400x300.format-webp.webpassets.worldwildlife.org/www-prd/im... https://assets.worldwildlife.org/www-prd/images/farm-plowed-WWspring2.2e16d0ba.fill-400x300.format-webp.webp — 200 — 23.1 KiB — 37 ms — h3https://assets.worldwildlife.org/www-prd/images/wwfcmsprodimagesGilln.2e16d0ba.fill-400x300.format-webp.webpassets.worldwildlife.org/www-prd/im... https://assets.worldwildlife.org/www-prd/images/wwfcmsprodimagesGilln.2e16d0ba.fill-400x300.format-webp.webp — 200 — 42.8 KiB — 36 ms — h3https://assets.worldwildlife.org/www-prd/images/_WW2155076.width-800.format-webp.webpassets.worldwildlife.org/www-prd/im... https://assets.worldwildlife.org/www-prd/images/_WW2155076.width-800.format-webp.webp — 200 — 82.2 KiB — 31 ms — h3https://www.worldwildlife.org/site.webmanifestwww.worldwildlife.org/site.webmanif... https://www.worldwildlife.org/site.webmanifest — 403 — 4.6 KiB — 28 ms — h3https://www.worldwildlife.org/favicon.icowww.worldwildlife.org/favicon.ico https://www.worldwildlife.org/favicon.ico — 200 — 1.8 KiB — 41 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 255ms · 203KB · $3/mo
www.worldwildlife.org
Other
Optional
Execution 137ms
Transfer 26 KB
Monthly Cost $2/mo
Unattributable
Other
Optional
Execution 62ms
Transfer 0 KB
Monthly Cost $1/mo
Google Tag Manager
Tag Manager
Optional
Execution 56ms
Transfer 177 KB
Unused 48%
Monthly Cost $1/mo

100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.

Why this matters

When third-party JS execution time exceeds your own, performance gains from frontend work are capped by code you don't own.

Learn more ▾

Every millisecond of third-party JS competes with your own for main-thread time. If their share is bigger than yours, optimization on your code base barely moves the needle. Audit, defer, or remove third-parties before further frontend optimization. Use Lighthouse's third-party audit to identify the worst offenders.

Source: web.dev

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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