Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

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

Mobile Desktop

Performance

Accessibility

Best Practices

SEO

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

1.53 s

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

8.08 s

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

123 ms

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

0.005

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

3.68 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.

8.96 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

10 PASS 4 REVIEW 1 FIX

Page Weight Budget

Action

10.7 MB transferred, 43 requests

FIX

10.7 MB transferred, 43 requests

Page weighs 12.5 MB (10.7 MB transferred)

Images are 1.5 MB — compress or use modern formats

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Got: 1.5 MB

43 HTTP requests

Estimated 2.3 g CO2 per page load

10.7 MB transferred

43 requests

2.3 g CO2 per page load

Other 8.7 MiB 81%

Images 1.5 MiB 14%

JavaScript 235.8 KiB 2%

Fonts 129.2 KiB 1%

CSS 104.3 KiB 1%

HTML 27.2 KiB 0%

Other 13.3 KiB 0%

Other 739 B 0%

0 2.4 MB 4.9 MB

Over budget

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Why this matters

Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.

Source: web.dev

Image Optimization

22 images, 0 KB saveable

REVIEW

22 images, 0 KB saveable

All images are well-optimized

22 images 1.5 MB

0 oversized -0 KB

12 legacy format

0 missing dimensions CLS risk

JS Execution Cost

Action

1812ms total JS execution

REVIEW

1812ms total JS execution

Unattributable: 640ms CPU time

https://iucn.org/sites/default/files/js/js_teBNjeQ...: 443ms CPU time

https://iucn.org/: 370ms CPU time

https://iucn.org/cdn-cgi/challenge-platform/script...: 215ms CPU time

https://www.googletagmanager.com/gtm.js?id=GTM-KTT...: 144ms CPU time

Third-party scripts: 784ms (43% of total)

Main Thread Breakdown

Script Evaluation 39% Other 32% Style & Layout 14% Parse HTML & CSS 5% Garbage Collection 4% Script Parsing & Compilation 3%

Script	Total	Scripting	Parse/Compile	Party
Unattributable	640ms	10ms	0ms	3rd
https://iucn.org/sites/default/files/js/js_teBNjeQ8bqfB9J0r4eyChJ08HtpnWlXUt9rnjJRdTSc.js?scope=footer&delta=0&language=en&theme=iucn_revamp&include=eJx1j4FqxSAMRX9In58kUdPW1RpJYt_e36920G2PDiQczoV4EyCuXul4zYUf9h9iApGKMjQfgDmTmwsFKFb0VXKdTSRGl7g3KI_E1EJXpWoSKBR4IbuAC-yZWEzusXr8zNqo9eYushI5N_3OGXfY2vsvv6PB9miXo_zxG9buC9S5w4xmLcDkzmmOFaunMHWJoJmqexdGsGAc5GUBPlpfwp4iGekNecqyuIvunF9oR85VseptLhuUchyMWO_zQdKD_Jc2knx2fqLfcIZxtpuIt8cT7RB2GDsxjRLpC96lva8	443ms	364ms	19ms	1st
https://iucn.org/	370ms	49ms	4ms	1st
https://iucn.org/cdn-cgi/challenge-platform/scripts/jsd/main.js	215ms	208ms	2ms	1st
https://www.googletagmanager.com/gtm.js?id=GTM-KTTKSGS	144ms	111ms	32ms	3rd

JS Bundles

4 scripts, 108 KB unused

REVIEW

4 scripts, 108 KB unused

https://www.googletagmanager.com/gtm.js?id=GTM-KTT...: 65 KB unused (49%)

Consider code splitting or tree shaking to reduce unused code.

https://iucn.org/sites/default/files/js/js_teBNjeQ...: 43 KB unused (61%)

Consider code splitting or tree shaking to reduce unused code.

Total unused JavaScript: 108 KB

108 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://www.googletagmanager.com/gtm.js?id=GTM-KTTKSGS	132 KB	65 KB (49%)	✓	3rd
https://iucn.org/sites/default/files/js/js_teBNjeQ8bqfB9J0r4eyChJ08HtpnWlXUt9rnjJRdTSc.js?scope=footer&delta=0&language=en&theme=iucn_revamp&include=eJx1j4FqxSAMRX9In58kUdPW1RpJYt_e36920G2PDiQczoV4EyCuXul4zYUf9h9iApGKMjQfgDmTmwsFKFb0VXKdTSRGl7g3KI_E1EJXpWoSKBR4IbuAC-yZWEzusXr8zNqo9eYushI5N_3OGXfY2vsvv6PB9miXo_zxG9buC9S5w4xmLcDkzmmOFaunMHWJoJmqexdGsGAc5GUBPlpfwp4iGekNecqyuIvunF9oR85VseptLhuUchyMWO_zQdKD_Jc2knx2fqLfcIZxtpuIt8cT7RB2GDsxjRLpC96lva8	70 KB	43 KB (61%)	✓	1st
https://iucn.org/libraries/klaro/dist/klaro-no-translations-no-css.js?tduwtt	21 KB	—	✓	1st
https://iucn.org/cdn-cgi/challenge-platform/h/b/scripts/jsd/0b8fb825cb67/main.js?	12 KB	—	✓	1st

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

Page Weight Inventory

Action

43 resources · 10.7 MB · 108 KB savings available

REVIEW

43 resources · 10.7 MB · 108 KB savings available

Page weight 9.7 MB over 1MB target

Got: 10.7 MB Expected: ≤ 1 MB

~108 KB of savings available

7 third-party resources (1% of weight)

5 resources over 200KB

43 resources · 10.7 MiB · 7 third-party 9.7 MiB over 1MB target

Media 81% · 8.7 MiB

Image 14% · 1.5 MiB

JavaScript 2% · 235.8 KiB

Font 1% · 129.2 KiB

CSS 1% · 104.3 KiB

Document 0% · 27.2 KiB

Other 0% · 902 B

~107.6 KiB of savings available

Remove unused JavaScript: 107.6 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

43 resources			10.7 MiB

A+

Third-Party Impact

1% third-party, 0 ms blocking

PASS

1% third-party, 0 ms blocking

Third-party code accounts for 1% of page weight (132.4 KiB of 10.7 MiB)

Third-party blocking time is low (0 ms)

99%

First-party Third-party

A+

Text Compression

All text resources are compressed

PASS

All text resources are compressed

All text resources are properly compressed.

A+

Font Loading

4 fonts (129 KB)

PASS

4 fonts (129 KB)

4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

129 KB total

Render-blocking

of 4

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

HelveticaNeueLTStd-Roma... woff2 swap

Size 14 KB

Load time 68 ms

Start 280 ms

Risk FOUT — text flashes from fallback to web font

IBMPlexSerif-Light.woff2 woff2 swap

Size 51 KB

Load time 68 ms

Start 282 ms

Risk FOUT — text flashes from fallback to web font

HelveticaNeueLTStd-Bd.w... woff2 swap

Size 14 KB

Load time 69 ms

Start 282 ms

Risk FOUT — text flashes from fallback to web font

IBMPlexSerif-SemiBold.w... woff2 swap

Size 51 KB

Load time 68 ms

Start 282 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

No caching issues found

All static resources have appropriate caching headers.

A+

Critical Rendering Path

No render-blocking resources

PASS

No render-blocking resources

No render-blocking resources detected

A+

Resource Hints

No optimization needed

PASS

No optimization needed

No resource hint issues

A+

Render-Blocking Resources

No render-blocking resources detected

PASS

No render-blocking resources detected

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=3600 (1 hour)

PASS

max-age=3600 (1 hour)

Cache-Control header is set

Got: max-age=3600, public

Effective TTL: 1 hour (max-age=3600)

Last-Modified header present

Cache-Control

max-age=3600, public

Directive	Value	Meaning
max-age	3600	Cache for 1 hour
public	—	Any cache may store this response

Effective TTL: 3600 seconds

Network Waterfall

43 requests over 1903ms

INFO

HTML JavaScript CSS Images Fonts XHR/Fetch Other

Third-Party Script Cost

Per-script blocking time, transfer cost, and cache headers

INFO

43% of JavaScript execution is third-party

First-party Third-party 784ms · 132KB · $10/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
Unattributable Unattributable	Other	640ms	0 KB	—	$8/mo	Costly
Google Tag Manager www.googletagmanager.com	Tag Manager	144ms	132 KB	49%	$2/mo	Optional

Unattributable

Other

Costly

Execution 640ms

Transfer 0 KB

Monthly Cost $8/mo

Google Tag Manager

Tag Manager

Optional

Execution 144ms

Transfer 132 KB

Unused 49%

Monthly Cost $2/mo

These scripts may cost more than they're worth

Unattributable adds 640ms and costs ~$8/month

43% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

Learn more ▾

Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

Unattributable takes 640ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

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

Source: web.dev

How third-party costs are calculated

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