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https://ourworldindata.org

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
77
GRADE
C
FIX
4
REVIEW
2
PASS
9
INFO
2

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

Mobile Desktop
75
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
81
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
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.

1.09 s

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

1.75 s

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

1.25 s

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

0.039

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

2.87 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.

10.75 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
F
Page Weight Budget
Action
2.9 MB transferred, 56 requests
FIX
2.9 MB transferred, 56 requests
Warning::
Page weighs 7.6 MB (2.9 MB transferred)
Warning::
JavaScript is 1.3 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.3 MB
Warning::
Images are 1.2 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 1.2 MB
Info::
Fonts are 303 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 303 KB
Info::
56 HTTP requests
Info::
Estimated 0.60 g CO2 per page load
2.9 MB / 2.4 MB budget
2.9 MB transferred
56 requests
0.60 g CO2 per page load
JavaScript 1.3 MiB 44%
Images 1.2 MiB 41%
Fonts 303.2 KiB 10%
Other 103.1 KiB 4%
HTML 39.0 KiB 1%
Other 9.8 KiB 0%
CSS 40 B 0%
Other 35 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

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

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

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

D
JS Execution Cost
Action
3490ms total JS execution
FIX
3490ms total JS execution
Warning::
Unattributable: 1481ms CPU time
Warning::
https://ourworldindata.org/assets/owid.mjs: 932ms CPU time
Warning::
https://ourworldindata.org/: 687ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-N2D...: 215ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-RSY8...: 175ms CPU time
Warning::
Third-party scripts: 1871ms (54% of total)

Main Thread Breakdown

Script Evaluation 46% Other 29% Style & Layout 15% Rendering 4%
ScriptTotalScriptingParse/CompileParty
Unattributable1481ms576ms0ms3rd
https://ourworldindata.org/assets/owid.mjs932ms708ms12ms1st
https://ourworldindata.org/687ms15ms19ms1st
https://www.googletagmanager.com/gtm.js?id=GTM-N2D4V8S215ms174ms39ms3rd
https://www.googletagmanager.com/gtag/js?id=G-RSY8NMC3MT&cx=c&gtm=4e64h1175ms143ms31ms3rd
F
JS Bundles
Action
4 scripts, 709 KB unused
FIX
4 scripts, 709 KB unused
Warning::
https://ourworldindata.org/assets/owid.mjs: 585 KB unused (59%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-RSY8...: 64 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-N2D...: 60 KB unused (46%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 709 KB
709 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://ourworldindata.org/assets/owid.mjs988 KB585 KB (59%)✓1st
https://www.googletagmanager.com/gtag/js?id=G-RSY8NMC3MT&cx=c&gtm=4e64h1152 KB64 KB (42%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-N2D4V8S130 KB60 KB (46%)✓3rd
https://static.cloudflareinsights.com/beacon.min.js11 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

D
Page Weight Inventory
Action
56 resources · 2.9 MB · 709 KB savings available
FIX
56 resources · 2.9 MB · 709 KB savings available
Warning::
Page weight 1.9 MB over 1MB target
Got: 2.9 MB Expected: ≤ 1 MB
Info::
~709 KB of savings available
Info::
9 third-party resources (10% of weight)
Info::
1 resources over 200KB
56 resources · 2.9 MiB · 9 third-party 1.9 MiB over 1MB target
JavaScript 44% · 1.3 MiB
Image 41% · 1.2 MiB
Font 10% · 303.2 KiB
Other 4% · 103.1 KiB
Document 1% · 39.0 KiB
CSS 0% · 40 B

~709.3 KiB of savings available

Remove unused JavaScript: 709.3 KiB
B
Image Optimization
22 images, 0 KB saveable
REVIEW
22 images, 0 KB saveable
Info::
All images are well-optimized
22 images 1.2 MB
0 oversized -0 KB
9 legacy format
0 missing dimensions CLS risk
B
HTTP Caching
no-cache
REVIEW
no-cache
Info::
Cache-Control header is set
Got: no-cache
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

no-cache

DirectiveValueMeaning
no-cache—Cache but always revalidate first
A+
Third-Party Impact
10% third-party, 0 ms blocking
PASS
10% third-party, 0 ms blocking
Info::
Third-party code accounts for 10% of page weight (294.4 KiB of 2.9 MiB)
Info::
Third-party blocking time is low (0 ms)
90%
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+
Font Loading
9 fonts (303 KB)
PASS
9 fonts (303 KB)
Info::
9 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

9

303 KB total

Render-blocking

0

of 9

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 1.1 s LCP 1.8 shttps://ourworldindata.org/fonts/LatoLatin-Regular.woff2LatoLatin-Regular.woff2 https://ourworldindata.org/fonts/LatoLatin-Regular.woff2 — 33.9 KiB — 27 ms — font-display: swaphttps://ourworldindata.org/fonts/LatoLatin-Black.woff2LatoLatin-Black.woff2 https://ourworldindata.org/fonts/LatoLatin-Black.woff2 — 33.2 KiB — 74 ms — font-display: swaphttps://ourworldindata.org/fonts/LatoLatin-Medium.woff2LatoLatin-Medium.woff2 https://ourworldindata.org/fonts/LatoLatin-Medium.woff2 — 34.3 KiB — 96 ms — font-display: swaphttps://ourworldindata.org/fonts/PlayfairDisplayLatin-SemiBold.woff2PlayfairDisplayLatin-Se... https://ourworldindata.org/fonts/PlayfairDisplayLatin-SemiBold.woff2 — 31.4 KiB — 108 ms — font-display: swaphttps://ourworldindata.org/fonts/PlayfairDisplayLatin-Bold.woff2PlayfairDisplayLatin-Bo... https://ourworldindata.org/fonts/PlayfairDisplayLatin-Bold.woff2 — 31.4 KiB — 105 ms — font-display: swaphttps://ourworldindata.org/fonts/LatoLatin-MediumItalic.woff2LatoLatin-MediumItalic.... https://ourworldindata.org/fonts/LatoLatin-MediumItalic.woff2 — 35.4 KiB — 105 ms — font-display: swaphttps://ourworldindata.org/fonts/LatoLatin-Bold.woff2LatoLatin-Bold.woff2 https://ourworldindata.org/fonts/LatoLatin-Bold.woff2 — 34.0 KiB — 106 ms — font-display: swaphttps://ourworldindata.org/fonts/LatoLatin-Semibold.woff2LatoLatin-Semibold.woff2 https://ourworldindata.org/fonts/LatoLatin-Semibold.woff2 — 34.1 KiB — 97 ms — font-display: swaphttps://ourworldindata.org/fonts/LatoLatin-Italic.woff2LatoLatin-Italic.woff2 https://ourworldindata.org/fonts/LatoLatin-Italic.woff2 — 35.5 KiB — 106 ms — font-display: swap
LatoLatin-Regular.woff2 woff2 swap
Size 34 KB
Load time 27 ms
Start 149 ms
Risk FOUT — text flashes from fallback to web font
LatoLatin-Black.woff2 woff2 swap
Size 33 KB
Load time 74 ms
Start 267 ms
Risk FOUT — text flashes from fallback to web font
LatoLatin-Medium.woff2 woff2 swap
Size 34 KB
Load time 96 ms
Start 267 ms
Risk FOUT — text flashes from fallback to web font
PlayfairDisplayLatin-Se... woff2 swap
Size 31 KB
Load time 108 ms
Start 267 ms
Risk FOUT — text flashes from fallback to web font
PlayfairDisplayLatin-Bo... woff2 swap
Size 31 KB
Load time 105 ms
Start 267 ms
Risk FOUT — text flashes from fallback to web font
LatoLatin-MediumItalic.... woff2 swap
Size 35 KB
Load time 105 ms
Start 271 ms
Risk FOUT — text flashes from fallback to web font
LatoLatin-Bold.woff2 woff2 swap
Size 34 KB
Load time 106 ms
Start 271 ms
Risk FOUT — text flashes from fallback to web font
LatoLatin-Semibold.woff2 woff2 swap
Size 34 KB
Load time 97 ms
Start 272 ms
Risk FOUT — text flashes from fallback to web font
LatoLatin-Italic.woff2 woff2 swap
Size 36 KB
Load time 106 ms
Start 272 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
4 hints, 0 missing preconnects
PASS
4 hints, 0 missing preconnects
Info::
Page uses 4 resource hint(s)

Current Resource Hints

preconnect
—
preload
4
dns-prefetch
—
prefetch
—

4 resource hints configured

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

Network Waterfall
56 requests over 1366ms
INFO
0 ms 500 ms 1.0 s 1.5 s FCP 1.1 s LCP 1.8 shttps://ourworldindata.org// https://ourworldindata.org/ — 200 — 39.0 KiB — 143 ms — h2https://ourworldindata.org/images/biweekly-newsletter.webp/images/biweekly-newsletter.webp https://ourworldindata.org/images/biweekly-newsletter.webp — 200 — 40 B — 33 ms — h2https://ourworldindata.org/images/data-insights.webp/images/data-insights.webp https://ourworldindata.org/images/data-insights.webp — 200 — 40 B — 33 ms — h2https://ourworldindata.org/assets/owid.mjs/assets/owid.mjs https://ourworldindata.org/assets/owid.mjs — 200 — 988.0 KiB — 264 ms — h2https://ourworldindata.org/assets/owid.css/assets/owid.css https://ourworldindata.org/assets/owid.css — 200 — 40 B — 35 ms — h2https://ourworldindata.org/fonts/LatoLatin-Regular.woff2/fonts/LatoLatin-Regular.woff2 https://ourworldindata.org/fonts/LatoLatin-Regular.woff2 — 200 — 33.9 KiB — 27 ms — h2https://static.cloudflareinsights.com/beacon.min.jsstatic.cloudflareinsights.com/beaco... https://static.cloudflareinsights.com/beacon.min.js — 200 — 10.7 KiB — 90 ms — h2https://www.googletagmanager.com/gtm.js?id=GTM-N2D4V8Swww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-N2D4V8S — 200 — 130.5 KiB — 158 ms — h2https://ourworldindata.org/images/world.svg/images/world.svg https://ourworldindata.org/images/world.svg — 200 — 11.6 KiB — 55 ms — h3https://ourworldindata.org/explorer-thumbnail.webp/explorer-thumbnail.webp https://ourworldindata.org/explorer-thumbnail.webp — 200 — 23.4 KiB — 71 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/e8c1792e-598e-4cd7-7a1a-309ed38b3800/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/e8c1792e-598e-4cd7-7a1a-309ed38b3800/w=850 — 200 — 3.8 KiB — 49 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/c0176bc5-b971-47b0-8ff3-c86cdfac9800/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/c0176bc5-b971-47b0-8ff3-c86cdfac9800/w=850 — 200 — 1.7 KiB — 47 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/014e8530-1d3d-409d-136d-467639157700/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/014e8530-1d3d-409d-136d-467639157700/w=850 — 200 — 35.8 KiB — 115 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/b18a3db6-93e7-4e72-3afa-ffae811d6800/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/b18a3db6-93e7-4e72-3afa-ffae811d6800/w=850 — 200 — 3.5 KiB — 83 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/e3b40748-b390-4e40-46f6-2db3a54d0f00/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/e3b40748-b390-4e40-46f6-2db3a54d0f00/w=850 — 200 — 56.3 KiB — 119 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/2b579c45-b1ce-4f08-eef8-04342c3ef500/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/2b579c45-b1ce-4f08-eef8-04342c3ef500/w=850 — 200 — 67.6 KiB — 122 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/817073af-eee5-4215-d0f6-b6f36c5fcb00/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/817073af-eee5-4215-d0f6-b6f36c5fcb00/w=850 — 200 — 90.3 KiB — 130 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/92713fbe-c3e6-44cf-f2ed-39f05492b400/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/92713fbe-c3e6-44cf-f2ed-39f05492b400/w=850 — 200 — 76.2 KiB — 127 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/23d16973-2578-46b6-fb5d-efcb6d0a1200/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/23d16973-2578-46b6-fb5d-efcb6d0a1200/w=850 — 200 — 66.1 KiB — 121 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/8a2c84fa-1d44-485f-d16b-36a0c6272d00/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/8a2c84fa-1d44-485f-d16b-36a0c6272d00/w=850 — 200 — 80.1 KiB — 128 ms — h3https://ourworldindata.org/grapher/child-mortality.png?time=earliest..latest&imWidth=850/grapher/child-mortality.png?time=e... https://ourworldindata.org/grapher/child-mortality.png?time=earliest..latest&imWidth=850 — 200 — 83.9 KiB — 128 ms — h3https://ourworldindata.org/grapher/share-of-population-in-extreme-poverty.png?imWidth=850/grapher/share-of-population-in-ext... https://ourworldindata.org/grapher/share-of-population-in-extreme-poverty.png?imWidth=850 — 200 — 144.4 KiB — 130 ms — h3https://ourworldindata.org/grapher/life-expectancy.png?imWidth=850/grapher/life-expectancy.png?imWidt... https://ourworldindata.org/grapher/life-expectancy.png?imWidth=850 — 200 — 73.8 KiB — 129 ms — h3https://ourworldindata.org/grapher/co-emissions-per-capita.png?tab=chart&country=USA~GBR~CHN~ZAF~PAN&imWidth=850/grapher/co-emissions-per-capita.pn... https://ourworldindata.org/grapher/co-emissions-per-capita.png?tab=chart&country=USA~GBR~CHN~ZAF~PAN&imWidth=850 — 200 — 71.8 KiB — 129 ms — h3https://ourworldindata.org/fonts/LatoLatin-Black.woff2/fonts/LatoLatin-Black.woff2 https://ourworldindata.org/fonts/LatoLatin-Black.woff2 — 200 — 33.2 KiB — 74 ms — h3https://ourworldindata.org/fonts/LatoLatin-Medium.woff2/fonts/LatoLatin-Medium.woff2 https://ourworldindata.org/fonts/LatoLatin-Medium.woff2 — 200 — 34.3 KiB — 96 ms — h3https://ourworldindata.org/fonts/PlayfairDisplayLatin-SemiBold.woff2/fonts/PlayfairDisplayLatin-SemiBol... https://ourworldindata.org/fonts/PlayfairDisplayLatin-SemiBold.woff2 — 200 — 31.4 KiB — 108 ms — h3https://ourworldindata.org/fonts/PlayfairDisplayLatin-Bold.woff2/fonts/PlayfairDisplayLatin-Bold.wo... https://ourworldindata.org/fonts/PlayfairDisplayLatin-Bold.woff2 — 200 — 31.4 KiB — 105 ms — h3https://ourworldindata.org/fonts/LatoLatin-MediumItalic.woff2/fonts/LatoLatin-MediumItalic.woff2 https://ourworldindata.org/fonts/LatoLatin-MediumItalic.woff2 — 200 — 35.4 KiB — 105 ms — h3https://ourworldindata.org/fonts/LatoLatin-Bold.woff2/fonts/LatoLatin-Bold.woff2 https://ourworldindata.org/fonts/LatoLatin-Bold.woff2 — 200 — 34.0 KiB — 106 ms — h3
0 ms 500 ms 1.0 s 1.5 s FCP 1.1 s LCP 1.8 shttps://ourworldindata.org// https://ourworldindata.org/ — 200 — 39.0 KiB — 143 ms — h2https://ourworldindata.org/images/biweekly-newsletter.webp/images/biweekly-newsletter.webp https://ourworldindata.org/images/biweekly-newsletter.webp — 200 — 40 B — 33 ms — h2https://ourworldindata.org/images/data-insights.webp/images/data-insights.webp https://ourworldindata.org/images/data-insights.webp — 200 — 40 B — 33 ms — h2https://ourworldindata.org/assets/owid.mjs/assets/owid.mjs https://ourworldindata.org/assets/owid.mjs — 200 — 988.0 KiB — 264 ms — h2https://ourworldindata.org/assets/owid.css/assets/owid.css https://ourworldindata.org/assets/owid.css — 200 — 40 B — 35 ms — h2https://ourworldindata.org/fonts/LatoLatin-Regular.woff2/fonts/LatoLatin-Regular.woff2 https://ourworldindata.org/fonts/LatoLatin-Regular.woff2 — 200 — 33.9 KiB — 27 ms — h2https://static.cloudflareinsights.com/beacon.min.jsstatic.cloudflareinsights.com/beaco... https://static.cloudflareinsights.com/beacon.min.js — 200 — 10.7 KiB — 90 ms — h2https://www.googletagmanager.com/gtm.js?id=GTM-N2D4V8Swww.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-N2D4V8S — 200 — 130.5 KiB — 158 ms — h2https://ourworldindata.org/images/world.svg/images/world.svg https://ourworldindata.org/images/world.svg — 200 — 11.6 KiB — 55 ms — h3https://ourworldindata.org/explorer-thumbnail.webp/explorer-thumbnail.webp https://ourworldindata.org/explorer-thumbnail.webp — 200 — 23.4 KiB — 71 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/e8c1792e-598e-4cd7-7a1a-309ed38b3800/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/e8c1792e-598e-4cd7-7a1a-309ed38b3800/w=850 — 200 — 3.8 KiB — 49 ms — h3https://ourworldindata.org/cdn-cgi/imagedelivery/qLq-8BTgXU8yG0N6HnOy8g/c0176bc5-b971-47b0-8ff3-c86cdfac9800/w=850/cdn-cgi/imagedelivery/qLq-8BTgXU8y... 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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
54% of JavaScript execution is third-party
First-party Third-party 1871ms · 283KB · €20/mo
Unattributable
Other
Costly
Execution 1481ms
Transfer 0 KB
Monthly Cost €16/mo
Google Tag Manager
Tag Manager
Costly
Execution 215ms
Transfer 130 KB
Unused 46%
Monthly Cost €2/mo
Google Tag Manager
Tag Manager
Optional
Execution 175ms
Transfer 152 KB
Unused 42%
Monthly Cost €2/mo

These scripts may cost more than they're worth

  • Unattributable adds 1481ms and costs ~€16/month
  • Google Tag Manager adds 215ms and costs ~€2/month

54% 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 1481ms 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

Google Tag Manager takes 215ms 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.

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