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https://cbs.nl

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
86
GRADE
B
FIX
2
REVIEW
4
PASS
9
INFO
2

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

Mobile Desktop
61
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
95
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
100
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.

4.28 s

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

6.89 s

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

148 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.

6.00 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.

7.93 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 4 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.

C
Image Optimization
Action
14 images, 0 KB saveable
REVIEW
14 images, 0 KB saveable
Warning::
https://cdn.cbs.nl/images/6a48317652416a4f367a4e66... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.cbs.nl/images/4f64652b416349705a534957... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.cbs.nl/images/41735a424f73476f73774e6b... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.cbs.nl/icons/navigation/cbs-logo-brand... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.cbs.nl/images/337a6156312f6d7935784a43... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.cbs.nl/images/324844614d3875744a694568... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.cbs.nl/Content/images/placeholder.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://api.eu.kaltura.com/p/139/thumbnail/entry_i... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
14 images 297 KB
0 oversized -0 KB
14 legacy format
8 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

C
JS Execution Cost
Action
1227ms total JS execution
REVIEW
1227ms total JS execution
Warning::
https://www.cbs.nl/: 412ms CPU time
Info::
https://cbs.containers.piwik.pro/7cd61318-6d21-477...: 217ms CPU time
Info::
Unattributable: 208ms CPU time
Info::
https://collect.mopinion.com/assets/surveys/2.0/js...: 172ms CPU time
Info::
https://deploy.mopinion.com/js/pastease.js: 156ms CPU time
Warning::
Third-party scripts: 1227ms (100% of total)

Main Thread Breakdown

Script Evaluation 38% Style & Layout 23% Other 23% Script Parsing & Compilation 7% Rendering 5%
ScriptTotalScriptingParse/CompileParty
https://www.cbs.nl/412ms23ms6ms3rd
https://cbs.containers.piwik.pro/7cd61318-6d21-4775-b1b2-64ec78d416e1.js?use_secure_cookies217ms162ms51ms3rd
Unattributable208ms5ms0ms3rd
https://collect.mopinion.com/assets/surveys/2.0/js/survey.min.js?v=18082023172ms102ms13ms3rd
https://deploy.mopinion.com/js/pastease.js156ms118ms4ms3rd
https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js63ms46ms7ms3rd
B
JS Bundles
8 scripts, 64 KB unused
REVIEW
8 scripts, 64 KB unused
Warning::
https://cbs.containers.piwik.pro/7cd61318-6d21-477...: 34 KB unused (35%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://collect.mopinion.com/assets/surveys/2.0/js...: 29 KB unused (52%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 64 KB
64 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://cbs.containers.piwik.pro/7cd61318-6d21-4775-b1b2-64ec78d416e1.js?use_secure_cookies100 KB34 KB (35%)✓3rd
https://collect.mopinion.com/assets/surveys/2.0/js/survey.min.js?v=1808202358 KB29 KB (52%)✓3rd
https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js28 KB—✓3rd
https://cdn.jsdelivr.net/npm/vanilla-lazyload@17.3.0/dist/lazyload.min.js3 KB—✓3rd
https://www.cbs.nl/content/js/cbs-v5/cbs.min.js7 KB—✓3rd
https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.js24 KB—✓3rd
https://deploy.mopinion.com/js/pastease.js14 KB—✓3rd
https://cbs.piwik.pro/ppms.js26 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
Page Weight Budget
917 KB transferred, 40 requests
PASS
917 KB transferred, 40 requests
Info::
Page weighs 1.9 MB (917 KB transferred)
Info::
40 HTTP requests
Info::
Estimated 0.19 g CO2 per page load
917 KB / 2.4 MB budget
917 KB transferred
40 requests
0.19 g CO2 per page load
Images 297.0 KiB 32%
JavaScript 260.0 KiB 28%
Fonts 197.6 KiB 22%
HTML 65.4 KiB 7%
CSS 53.3 KiB 6%
Other 27.8 KiB 3%
Other 15.3 KiB 2%
Other 965 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Under budget
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
5 fonts (198 KB)
PASS
5 fonts (198 KB)
Info::
5 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

5

198 KB total

Render-blocking

0

of 5

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s FCP 4.3 s LCP 6.9 shttps://cdn.cbs.nl/cdn/fonts/soho-medium.woff2soho-medium.woff2 https://cdn.cbs.nl/cdn/fonts/soho-medium.woff2 — 21.4 KiB — 229 ms — font-display: swaphttps://cdn.cbs.nl/cdn/fonts/akko-regular.woff2akko-regular.woff2 https://cdn.cbs.nl/cdn/fonts/akko-regular.woff2 — 20.5 KiB — 237 ms — font-display: swaphttps://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/fonts/fontawesome-webfont.woff2?v=4.7.0fontawesome-webfont.woff2 https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/fonts/fontawesome-webfont.woff2?v=4.7.0 — 76.0 KiB — 137 ms — font-display: swaphttps://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.5.0/fonts/fontawesome-webfont.woff2?v=4.5.0fontawesome-webfont.woff2 https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.5.0/fonts/fontawesome-webfont.woff2?v=4.5.0 — 65.7 KiB — 42 ms — font-display: swaphttps://gstatic.mopinion.com/s/opensans/v44/memSYaGs126MiZpBA-UvWbX2vVnXBbObj2OVZyOOSr4dVJWUgsjZ0B4gaVIUx6EQ.woff2memSYaGs126MiZpBA-UvWbX... https://gstatic.mopinion.com/s/opensans/v44/memSYaGs126MiZpBA-UvWbX2vVnXBbObj2OVZyOOSr4dVJWUgsjZ0B4gaVIUx6EQ.woff2 — 13.9 KiB — 144 ms — font-display: swap
soho-medium.woff2 woff2 swap
Size 21 KB
Load time 229 ms
Start 190 ms
Risk FOUT — text flashes from fallback to web font
akko-regular.woff2 woff2 swap
Size 21 KB
Load time 237 ms
Start 190 ms
Risk FOUT — text flashes from fallback to web font
fontawesome-webfont.woff2 unknown swap
Size 76 KB
Load time 137 ms
Start 190 ms
Risk FOUT — text flashes from fallback to web font
fontawesome-webfont.woff2 unknown swap
Size 66 KB
Load time 42 ms
Start 416 ms
Risk FOUT — text flashes from fallback to web font
memSYaGs126MiZpBA-UvWbX... woff2 swap
Size 14 KB
Load time 144 ms
Start 2.9 s
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)

Fixing the unchecked items could save ~43 KB and ~86 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
7 hints, 0 missing preconnects
PASS
7 hints, 0 missing preconnects
Info::
Page uses 7 resource hint(s)

Current Resource Hints

preconnect
—
preload
3
dns-prefetch
4
prefetch
—

7 resource hints configured

A
Page Weight Inventory
40 resources · 917 KB · 64 KB savings available
PASS
40 resources · 917 KB · 64 KB savings available
Info::
Within 1MB page-weight target
Got: 917 KB
Info::
~64 KB of savings available
Warning::
39 third-party resources (100% of weight)
40 resources · 917.3 KiB · 39 third-party Within 1MB page-weight target
Image 34% · 312.2 KiB
JavaScript 28% · 260.0 KiB
Font 22% · 197.6 KiB
Document 7% · 65.4 KiB
CSS 6% · 53.3 KiB
Other 3% · 28.7 KiB

~63.7 KiB of savings available

Remove unused JavaScript: 63.7 KiB
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
Network Waterfall
40 requests over 3049ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s FCP 4.3 s LCP 6.9 shttps://cbs.nl// https://cbs.nl/ — 301 — 99 B — 95 ms — h2https://www.cbs.nl/www.cbs.nl/ https://www.cbs.nl/ — 200 — 65.4 KiB — 111 ms — h2https://cdn.cbs.nl/cdn/fonts/soho-medium.woff2cdn.cbs.nl/cdn/fonts/soho-medium.wo... https://cdn.cbs.nl/cdn/fonts/soho-medium.woff2 — 200 — 21.4 KiB — 229 ms — h2https://cdn.cbs.nl/cdn/fonts/akko-regular.woff2cdn.cbs.nl/cdn/fonts/akko-regular.w... https://cdn.cbs.nl/cdn/fonts/akko-regular.woff2 — 200 — 20.5 KiB — 237 ms — h2https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/fonts/fontawesome-webfont.woff2?v=4.7.0cdnjs.cloudflare.com/ajax/libs/font... https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/fonts/fontawesome-webfont.woff2?v=4.7.0 — 200 — 76.0 KiB — 137 ms — h3https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.csscdn.jsdelivr.net/npm/bootstrap@5.3.... https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.css — 200 — 32.9 KiB — 42 ms — h2https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.csscdnjs.cloudflare.com/ajax/libs/font... https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.css — 200 — 6.4 KiB — 103 ms — h3https://www.cbs.nl/content/css-v5/cbs.min.csswww.cbs.nl/content/css-v5/cbs.min.c... https://www.cbs.nl/content/css-v5/cbs.min.css — 200 — 10.5 KiB — 33 ms — h2https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.jscdnjs.cloudflare.com/ajax/libs/jque... https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js — 200 — 27.9 KiB — 138 ms — h3https://cdn.cbs.nl/icons/navigation/cbs-logo-brand-nl.svgcdn.cbs.nl/icons/navigation/cbs-log... https://cdn.cbs.nl/icons/navigation/cbs-logo-brand-nl.svg — 200 — 3.8 KiB — 215 ms — h2https://cdn.cbs.nl/images/324844614d3875744a694568663554434e62434b7a773d3d/900x450.jpgcdn.cbs.nl/images/324844614d3875744... https://cdn.cbs.nl/images/324844614d3875744a694568663554434e62434b7a773d3d/900x450.jpg — 200 — 108.8 KiB — 259 ms — h2https://www.cbs.nl/Content/images/placeholder.jpgwww.cbs.nl/Content/images/placehold... https://www.cbs.nl/Content/images/placeholder.jpg — 200 — 2.5 KiB — 40 ms — h2https://cdn.cbs.nl/cdn/images/site.webmanifestcdn.cbs.nl/cdn/images/site.webmanif... https://cdn.cbs.nl/cdn/images/site.webmanifest — 200 — 965 B — 85 ms — h2https://cdn.jsdelivr.net/npm/vanilla-lazyload@17.3.0/dist/lazyload.min.jscdn.jsdelivr.net/npm/vanilla-lazylo... https://cdn.jsdelivr.net/npm/vanilla-lazyload@17.3.0/dist/lazyload.min.js — 200 — 2.8 KiB — 6 ms — h2https://www.cbs.nl/content/js/cbs-v5/cbs.min.jswww.cbs.nl/content/js/cbs-v5/cbs.mi... https://www.cbs.nl/content/js/cbs-v5/cbs.min.js — 200 — 6.9 KiB — 36 ms — h2https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.jscdn.jsdelivr.net/npm/bootstrap@5.3.... https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.js — 200 — 24.0 KiB — 6 ms — h2https://api.eu.kaltura.com/p/139/thumbnail/entry_id/0_5pf53bcj/width/480/height/270/api.eu.kaltura.com/p/139/thumbnail/... https://api.eu.kaltura.com/p/139/thumbnail/entry_id/0_5pf53bcj/width/480/height/270/ — 200 — 63.6 KiB — 352 ms — http/1.1https://www.cbs.nl/content/css-v5/cbs-print.min.csswww.cbs.nl/content/css-v5/cbs-print... https://www.cbs.nl/content/css-v5/cbs-print.min.css — 200 — 1.5 KiB — 37 ms — h2https://cdn.cbs.nl/cdn/images/favicon.icocdn.cbs.nl/cdn/images/favicon.ico https://cdn.cbs.nl/cdn/images/favicon.ico — 200 — 15.2 KiB — 74 ms — h2https://cbs.containers.piwik.pro/7cd61318-6d21-4775-b1b2-64ec78d416e1.js?use_secure_cookiescbs.containers.piwik.pro/7cd61318-6... https://cbs.containers.piwik.pro/7cd61318-6d21-4775-b1b2-64ec78d416e1.js?use_secure_cookies — 200 — 100.1 KiB — 224 ms — h2https://deploy.mopinion.com/js/pastease.jsdeploy.mopinion.com/js/pastease.js https://deploy.mopinion.com/js/pastease.js — 200 — 13.9 KiB — 106 ms — h2https://cdn.cbs.nl/icons/navigation/hamburger.svgcdn.cbs.nl/icons/navigation/hamburg... https://cdn.cbs.nl/icons/navigation/hamburger.svg — 200 — 995 B — 60 ms — h2https://cdn.cbs.nl/icons/social-media/linkedin.svgcdn.cbs.nl/icons/social-media/linke... https://cdn.cbs.nl/icons/social-media/linkedin.svg — 200 — 1.3 KiB — 62 ms — h2https://cdn.cbs.nl/icons/social-media/facebook.svgcdn.cbs.nl/icons/social-media/faceb... https://cdn.cbs.nl/icons/social-media/facebook.svg — 200 — 1.0 KiB — 62 ms — h2https://cdn.cbs.nl/icons/social-media/instagram.svgcdn.cbs.nl/icons/social-media/insta... https://cdn.cbs.nl/icons/social-media/instagram.svg — 200 — 1.5 KiB — 62 ms — h2https://cdn.cbs.nl/icons/social-media/youtube.svgcdn.cbs.nl/icons/social-media/youtu... https://cdn.cbs.nl/icons/social-media/youtube.svg — 200 — 1.2 KiB — 62 ms — h2https://cdn.cbs.nl/icons/social-media/rss.svgcdn.cbs.nl/icons/social-media/rss.s... https://cdn.cbs.nl/icons/social-media/rss.svg — 200 — 1.3 KiB — 62 ms — h2https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.5.0/fonts/fontawesome-webfont.woff2?v=4.5.0cdnjs.cloudflare.com/ajax/libs/font... https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.5.0/fonts/fontawesome-webfont.woff2?v=4.5.0 — 200 — 65.7 KiB — 42 ms — h3https://deploy.mopinion.com/config/0hKjknX8sDlwkxS2UPuSVYXJsi3fxhR0se9Bmyvrdeploy.mopinion.com/config/0hKjknX8... https://deploy.mopinion.com/config/0hKjknX8sDlwkxS2UPuSVYXJsi3fxhR0se9Bmyvr — 200 — 1.7 KiB — 52 ms — h2https://cbs.piwik.pro/ppms.jscbs.piwik.pro/ppms.js https://cbs.piwik.pro/ppms.js — 200 — 26.0 KiB — 220 ms — h2
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s FCP 4.3 s LCP 6.9 shttps://cbs.nl// https://cbs.nl/ — 301 — 99 B — 95 ms — h2https://www.cbs.nl/www.cbs.nl/ https://www.cbs.nl/ — 200 — 65.4 KiB — 111 ms — h2https://cdn.cbs.nl/cdn/fonts/soho-medium.woff2cdn.cbs.nl/cdn/fonts/soho-medium.wo... https://cdn.cbs.nl/cdn/fonts/soho-medium.woff2 — 200 — 21.4 KiB — 229 ms — h2https://cdn.cbs.nl/cdn/fonts/akko-regular.woff2cdn.cbs.nl/cdn/fonts/akko-regular.w... https://cdn.cbs.nl/cdn/fonts/akko-regular.woff2 — 200 — 20.5 KiB — 237 ms — h2https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/fonts/fontawesome-webfont.woff2?v=4.7.0cdnjs.cloudflare.com/ajax/libs/font... https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/fonts/fontawesome-webfont.woff2?v=4.7.0 — 200 — 76.0 KiB — 137 ms — h3https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.csscdn.jsdelivr.net/npm/bootstrap@5.3.... https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.css — 200 — 32.9 KiB — 42 ms — h2https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.csscdnjs.cloudflare.com/ajax/libs/font... https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.css — 200 — 6.4 KiB — 103 ms — h3https://www.cbs.nl/content/css-v5/cbs.min.csswww.cbs.nl/content/css-v5/cbs.min.c... https://www.cbs.nl/content/css-v5/cbs.min.css — 200 — 10.5 KiB — 33 ms — h2https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.jscdnjs.cloudflare.com/ajax/libs/jque... https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js — 200 — 27.9 KiB — 138 ms — h3https://cdn.cbs.nl/icons/navigation/cbs-logo-brand-nl.svgcdn.cbs.nl/icons/navigation/cbs-log... https://cdn.cbs.nl/icons/navigation/cbs-logo-brand-nl.svg — 200 — 3.8 KiB — 215 ms — h2https://cdn.cbs.nl/images/324844614d3875744a694568663554434e62434b7a773d3d/900x450.jpgcdn.cbs.nl/images/324844614d3875744... https://cdn.cbs.nl/images/324844614d3875744a694568663554434e62434b7a773d3d/900x450.jpg — 200 — 108.8 KiB — 259 ms — h2https://www.cbs.nl/Content/images/placeholder.jpgwww.cbs.nl/Content/images/placehold... https://www.cbs.nl/Content/images/placeholder.jpg — 200 — 2.5 KiB — 40 ms — h2https://cdn.cbs.nl/cdn/images/site.webmanifestcdn.cbs.nl/cdn/images/site.webmanif... https://cdn.cbs.nl/cdn/images/site.webmanifest — 200 — 965 B — 85 ms — h2https://cdn.jsdelivr.net/npm/vanilla-lazyload@17.3.0/dist/lazyload.min.jscdn.jsdelivr.net/npm/vanilla-lazylo... https://cdn.jsdelivr.net/npm/vanilla-lazyload@17.3.0/dist/lazyload.min.js — 200 — 2.8 KiB — 6 ms — h2https://www.cbs.nl/content/js/cbs-v5/cbs.min.jswww.cbs.nl/content/js/cbs-v5/cbs.mi... https://www.cbs.nl/content/js/cbs-v5/cbs.min.js — 200 — 6.9 KiB — 36 ms — h2https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.jscdn.jsdelivr.net/npm/bootstrap@5.3.... https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.js — 200 — 24.0 KiB — 6 ms — 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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
100% of JavaScript execution is third-party
First-party Third-party 1227ms · 266KB · €13/mo
www.cbs.nl
Other
Costly
Execution 412ms
Transfer 65 KB
Monthly Cost €4/mo
cbs.containers.piwik.pro
Other
Costly
Execution 217ms
Transfer 100 KB
Unused 35%
Monthly Cost €2/mo
Unattributable
Other
Costly
Execution 208ms
Transfer 0 KB
Monthly Cost €2/mo
collect.mopinion.com
Other
Optional
Execution 172ms
Transfer 58 KB
Unused 52%
Monthly Cost €2/mo
deploy.mopinion.com
Other
Optional
Execution 156ms
Transfer 14 KB
Monthly Cost €2/mo
cdnjs
CDN
Optional
Execution 63ms
Transfer 28 KB
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • www.cbs.nl adds 412ms and costs ~€4/month
  • cbs.containers.piwik.pro adds 217ms and costs ~€2/month
  • Unattributable adds 208ms and costs ~€2/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.cbs.nl takes 412ms 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

cbs.containers.piwik.pro takes 217ms 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

Unattributable takes 208ms 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

52% of collect.mopinion.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

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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