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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
85
GRADE
B
FIX
1
REVIEW
3
PASS
8
INFO
2

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

Mobile Desktop
83
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
87
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
85
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
91
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.

942 ms

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

2.81 s

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

28 ms

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

0.000

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

1.02 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.

3.09 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
14
8 PASS 3 REVIEW 1 FIX
D
Page Weight Budget
Action
2.5 MB transferred, 24 requests
FIX
2.5 MB transferred, 24 requests
Warning::
Page weighs 2.9 MB (2.5 MB transferred)
Warning::
Images are 1.9 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 1.9 MB
Info::
CSS is 242 KB — consider purging unused styles
Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.
Got: 242 KB
Info::
24 HTTP requests
Info::
Estimated 0.52 g CO2 per page load
2.5 MB / 2.4 MB budget
2.5 MB transferred
24 requests
0.52 g CO2 per page load
Images 1.9 MiB 79%
CSS 242.2 KiB 10%
JavaScript 227.4 KiB 9%
Fonts 55.9 KiB 2%
HTML 10.5 KiB 0%
Other 852 B 0%
Other 545 B 0%
Other 462 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

Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.

Why this matters

CSS bundle is large — purge unused styles (PurgeCSS, Tailwind JIT) to reduce CSS payload.

Source: web.dev

B
Image Optimization
5 images, 0 KB saveable
REVIEW
5 images, 0 KB saveable
Warning::
https://www.un.org/en/img/splash/un-logo.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
5 images 1.9 MB
0 oversized -0 KB
5 legacy format
1 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

B
JS Bundles
5 scripts, 82 KB unused
REVIEW
5 scripts, 82 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-TK9B...: 61 KB unused (40%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://code.jquery.com/jquery-3.7.1.min.js: 21 KB unused (70%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 82 KB
82 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-TK9BQL5X7Z&cx=c&_slc=1155 KB61 KB (40%)✓3rd
https://code.jquery.com/jquery-3.7.1.min.js30 KB21 KB (70%)✓3rd
https://ssl.google-analytics.com/ga.js15 KB—✓3rd
https://www.un.org/fr/images/splash/splash.js6 KB—✓1st
https://www.google-analytics.com/analytics.js21 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

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Third-Party Impact
11% third-party, 0 ms blocking
PASS
11% third-party, 0 ms blocking
Info::
Third-party code accounts for 11% of page weight (287.8 KiB of 2.5 MiB)
Info::
Third-party blocking time is low (0 ms)
89%
First-party Third-party
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
443ms total JS execution
PASS
443ms total JS execution
Info::
Unattributable: 188ms CPU time
Info::
https://www.un.org/: 133ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-TK9B...: 121ms CPU time
Warning::
Third-party scripts: 310ms (70% of total)

Main Thread Breakdown

Other 40% Script Evaluation 35% Style & Layout 13% Script Parsing & Compilation 6% Parse HTML & CSS 4%
ScriptTotalScriptingParse/CompileParty
Unattributable188ms37ms0ms3rd
https://www.un.org/133ms4ms1ms1st
https://www.googletagmanager.com/gtag/js?id=G-TK9BQL5X7Z&cx=c&_slc=1121ms91ms25ms3rd
A+
Font Loading
2 fonts (56 KB)
PASS
2 fonts (56 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

56 KB total

Render-blocking

0

of 2

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 2.0 s 2.5 s FCP 942 ms LCP 2.8 shttps://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2KFO7CnqEu92Fr1ME7kSn66a... https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3yUBHMdazQ.woff2 — 36.7 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3iUBHMdazTgWw.woff2KFO7CnqEu92Fr1ME7kSn66a... https://fonts.gstatic.com/s/roboto/v51/KFO7CnqEu92Fr1ME7kSn66aGLdTylUAMa3iUBHMdazTgWw.woff2 — 19.2 KiB — 0 ms — font-display: swap
KFO7CnqEu92Fr1ME7kSn66a... woff2 swap
Size 37 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
KFO7CnqEu92Fr1ME7kSn66a... woff2 swap
Size 19 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Optimization checklist
  • Preload critical fonts (priority=high)
  • Use woff2 format for all fonts
  • Set font-display to swap, optional, or fallback
  • Subset large fonts (≤100 KB each)
A+
Resource Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A+
HTTP Caching
max-age=900 (15 minutes)
PASS
max-age=900 (15 minutes)
Info::
Cache-Control header is set
Got: public, max-age=900
Info::
Effective TTL: 15 minutes (max-age=900)
Info::
ETag present — enables conditional (304) responses
Info::
Last-Modified header present
Cache-Control

public, max-age=900

DirectiveValueMeaning
public—Any cache may store this response
max-age900Cache for 15 minutes
Effective TTL: 900 seconds
Network Waterfall
24 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
70% of JavaScript execution is third-party
First-party Third-party 310ms · 155KB · €3/mo
Unattributable
Other
Optional
Execution 188ms
Transfer 0 KB
Monthly Cost €2/mo
Google Tag Manager
Tag Manager
Optional
Execution 121ms
Transfer 155 KB
Unused 40%
Monthly Cost €1/mo

70% 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

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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