Skip to content
https://uva.nl

Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
74
GRADE
C
FIX
5
REVIEW
2
PASS
6
INFO
2

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

Mobile Desktop
80
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
100
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.
100
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.

1.78 s

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

2.21 s

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

19 ms

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

0.004

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

1.78 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.

2.39 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
6 PASS 2 REVIEW 5 FIX
F
Page Weight Budget
Action
2.7 MB transferred, 47 requests
FIX
2.7 MB transferred, 47 requests
Warning::
Page weighs 4.0 MB (2.7 MB transferred)
Warning::
JavaScript is 1.0 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.0 MB
Info::
CSS is 372 KB — consider purging unused styles
Remove unused CSS rules with tools like PurgeCSS to reduce stylesheet size.
Got: 372 KB
Info::
47 HTTP requests
Info::
Estimated 0.57 g CO2 per page load
2.7 MB / 2.4 MB budget
2.7 MB transferred
47 requests
0.57 g CO2 per page load
JavaScript 1.0 MiB 38%
Images 940.9 KiB 34%
CSS 372.4 KiB 13%
HTML 164.5 KiB 6%
Fonts 162.4 KiB 6%
Other 78.2 KiB 3%
Other 1.4 KiB 0%
Other 546 B 0%
Other 281 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

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

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 (2.7 MiB of 2.7 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
JS Bundles
Action
12 scripts, 565 KB unused
FIX
12 scripts, 565 KB unused
Warning::
https://www.uva.nl/webfiles/1765960941537/js/app.j...: 195 KB unused (66%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.uva.nl/webfiles/1765960941537/js/699.j...: 102 KB unused (75%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://siteimproveanalytics.com/js/siteanalyze_60...: 69 KB unused (67%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-44XG...: 66 KB unused (39%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-HX9...: 66 KB unused (33%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 565 KB
565 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.uva.nl/webfiles/1765960941537/js/app.js295 KB195 KB (66%)✓3rd
https://www.uva.nl/webfiles/1765960941537/js/699.js137 KB102 KB (75%)✓3rd
https://siteimproveanalytics.com/js/siteanalyze_6004849.js104 KB69 KB (67%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-44XGTNSN28&cx=c&gtm=4e64h1h1170 KB66 KB (39%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-HX98198 KB66 KB (33%)✓3rd
https://analytics.ic.uva.nl/matomo.js67 KB38 KB (57%)✓3rd
https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/config/TeX-AMS_HTML.js?V=2.7.454 KB30 KB (57%)✓3rd
https://www.uva.nl/webfiles/1765960941537/js/uvacookiebar.js3 KB—✓3rd
https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/MathJax.js?config=TeX-AMS_HTML17 KB—✓3rd
https://www.uva.nl/webfiles/1765960941537/js/4.js7 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

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

F
Page Weight Inventory
Action
47 resources · 2.7 MB · 565 KB savings available
FIX
47 resources · 2.7 MB · 565 KB savings available
Warning::
Page weight 1.7 MB over 1MB target
Got: 2.7 MB Expected: ≤ 1 MB
Info::
~565 KB of savings available
Warning::
46 third-party resources (100% of weight)
Info::
3 resources over 200KB
47 resources · 2.7 MiB · 46 third-party 1.7 MiB over 1MB target
JavaScript 38% · 1.0 MiB
Image 37% · 1018.4 KiB
CSS 13% · 372.4 KiB
Document 6% · 164.7 KiB
Font 6% · 162.4 KiB
Other 0% · 2.6 KiB

~565.5 KiB of savings available

Remove unused JavaScript: 565.5 KiB
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 Execution Cost
703ms total JS execution
REVIEW
703ms total JS execution
Info::
https://www.uva.nl/webfiles/1765960941537/js/app.j...: 214ms CPU time
Info::
https://www.uva.nl/: 155ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-HX9...: 122ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-44XG...: 82ms CPU time
Info::
Unattributable: 78ms CPU time
Warning::
Third-party scripts: 703ms (100% of total)

Main Thread Breakdown

Script Evaluation 41% Other 23% Style & Layout 18% Script Parsing & Compilation 9% Rendering 7%
ScriptTotalScriptingParse/CompileParty
https://www.uva.nl/webfiles/1765960941537/js/app.js214ms62ms7ms3rd
https://www.uva.nl/155ms6ms1ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-HX98122ms104ms16ms3rd
https://www.googletagmanager.com/gtag/js?id=G-44XGTNSN28&cx=c&gtm=4e64h1h182ms67ms15ms3rd
Unattributable78ms10ms0ms3rd
https://siteimproveanalytics.com/js/siteanalyze_6004849.js51ms20ms12ms3rd
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

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
18 images, 0 KB saveable
PASS
18 images, 0 KB saveable
Info::
All images are well-optimized
18 images 941 KB
0 oversized -0 KB
3 legacy format
0 missing dimensions CLS risk
A+
Font Loading
4 fonts (162 KB)
PASS
4 fonts (162 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

162 KB total

Render-blocking

0

of 4

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 FCP 1.8 s LCP 2.2 shttps://use.typekit.net/af/4db8bf/00000000000000007735d61c/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3l https://use.typekit.net/af/4db8bf/00000000000000007735d61c/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3 — 43.1 KiB — 20 ms — font-display: swaphttps://use.typekit.net/af/14f0be/000000000000000077586386/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3l https://use.typekit.net/af/14f0be/000000000000000077586386/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3 — 37.7 KiB — 22 ms — font-display: swaphttps://use.typekit.net/af/642cd4/000000000000000077587094/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n6&v=3l https://use.typekit.net/af/642cd4/000000000000000077587094/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n6&v=3 — 38.0 KiB — 22 ms — font-display: swaphttps://use.typekit.net/af/4f35a4/00000000000000007735d633/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n6&v=3l https://use.typekit.net/af/4f35a4/00000000000000007735d633/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n6&v=3 — 43.7 KiB — 23 ms — font-display: swap
l woff2 swap
Size 43 KB
Load time 20 ms
Start 505 ms
Risk FOUT — text flashes from fallback to web font
l woff2 swap
Size 38 KB
Load time 22 ms
Start 505 ms
Risk FOUT — text flashes from fallback to web font
l woff2 swap
Size 38 KB
Load time 22 ms
Start 507 ms
Risk FOUT — text flashes from fallback to web font
l woff2 swap
Size 44 KB
Load time 23 ms
Start 507 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
Network Waterfall
47 requests over 1838ms
INFO
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 1.8 s LCP 2.2 shttps://uva.nl// https://uva.nl/ — 301 — 651 B — 111 ms — h2https://www.uva.nl/www.uva.nl/ https://www.uva.nl/ — 200 — 164.5 KiB — 208 ms — h2https://www.uva.nl/webfiles/1765960941537/css/app.min.csswww.uva.nl/webfiles/1765960941537/c... https://www.uva.nl/webfiles/1765960941537/css/app.min.css — 200 — 359.2 KiB — 135 ms — h2https://www.uva.nl/webfiles/1765960941537/js/uvacookiebar.jswww.uva.nl/webfiles/1765960941537/j... https://www.uva.nl/webfiles/1765960941537/js/uvacookiebar.js — 200 — 3.2 KiB — 100 ms — h2https://www.uva.nl/webfiles/1765960941537/includes/home-research-nl/home-research-nl.csswww.uva.nl/webfiles/1765960941537/i... https://www.uva.nl/webfiles/1765960941537/includes/home-research-nl/home-research-nl.css — 200 — 3.3 KiB — 99 ms — h2https://www.uva.nl/webfiles/1765960941537/includes/home-overdeuva-nl/home-overdeuva-nl.csswww.uva.nl/webfiles/1765960941537/i... https://www.uva.nl/webfiles/1765960941537/includes/home-overdeuva-nl/home-overdeuva-nl.css — 200 — 2.9 KiB — 99 ms — h2https://www.uva.nl/webfiles/1765960941537/_favicon/manifest.jsonwww.uva.nl/webfiles/1765960941537/_... https://www.uva.nl/webfiles/1765960941537/_favicon/manifest.json — 200 — 1.4 KiB — 123 ms — h2https://www.uva.nl/webfiles/1765960941537/js/app.jswww.uva.nl/webfiles/1765960941537/j... https://www.uva.nl/webfiles/1765960941537/js/app.js — 200 — 295.0 KiB — 78 ms — h2https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/MathJax.js?config=TeX-AMS_HTMLcdnjs.cloudflare.com/ajax/libs/math... https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/MathJax.js?config=TeX-AMS_HTML — 200 — 17.3 KiB — 67 ms — h3https://www.googletagmanager.com/gtm.js?id=GTM-HX98www.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-HX98 — 200 — 197.7 KiB — 182 ms — h2https://use.typekit.net/emf5eij.cssuse.typekit.net/emf5eij.css https://use.typekit.net/emf5eij.css — 200 — 1.2 KiB — 9 ms — h2https://www.uva.nl/webfiles/1765960941537/css/print.min.csswww.uva.nl/webfiles/1765960941537/c... https://www.uva.nl/webfiles/1765960941537/css/print.min.css — 200 — 5.8 KiB — 40 ms — h2https://p.typekit.net/p.css?s=1&k=emf5eij&ht=tk&f=13378.13379.13380.13381.13382.13383.17265.17270.17272&a=13802896&app=typekit&e=cssp.typekit.net/p.css?s=1&k=emf5eij&h... https://p.typekit.net/p.css?s=1&k=emf5eij&ht=tk&f=13378.13379.13380.13381.13382.13383.17265.17270.17272&a=13802896&app=typekit&e=css — 200 — 172 B — 16 ms — h2https://analytics.ic.uva.nl/matomo.jsanalytics.ic.uva.nl/matomo.js https://analytics.ic.uva.nl/matomo.js — 200 — 66.7 KiB — 194 ms — http/1.1https://www.uva.nl/webfiles/1765960941537/icons/svg-logos.svgwww.uva.nl/webfiles/1765960941537/i... https://www.uva.nl/webfiles/1765960941537/icons/svg-logos.svg — 200 — 69.6 KiB — 40 ms — h2data:image/svg+xml;charset=utf8, %3Csvg height='20' viewBox='0 0 20 20' width='20' xmlns='http://ww…ww… data:image/svg+xml;charset=utf8, %3Csvg height='20' viewBox='0 0 20 20' width='20' xmlns='http://ww… — 200 — 0 B — 0 ms — datadata:image/svg+xml;charset=utf8, %3Csvg xmlns='http://www.w3.org/2000/svg' height='100' viewBox='0 …www.w3.org/2000/svg' height='100' v... data:image/svg+xml;charset=utf8, %3Csvg xmlns='http://www.w3.org/2000/svg' height='100' viewBox='0 … — 200 — 0 B — 0 ms — datahttps://www.uva.nl/binaries/_ht_1744634291608/1400x700-webp/content/gallery/evenementen/2025/minorweek/202504-kies-je-minor.pngwww.uva.nl/binaries/_ht_17446342916... https://www.uva.nl/binaries/_ht_1744634291608/1400x700-webp/content/gallery/evenementen/2025/minorweek/202504-kies-je-minor.png — 200 — 39.7 KiB — 58 ms — h2https://www.uva.nl/webfiles/1765960941537/includes/home-research-nl/img/seven-klimaatinitiatief-Still.pngwww.uva.nl/webfiles/1765960941537/i... https://www.uva.nl/webfiles/1765960941537/includes/home-research-nl/img/seven-klimaatinitiatief-Still.png — 200 — 294.1 KiB — 70 ms — h2https://www.uva.nl/binaries/_ht_1776764836666/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/vooroordelen-en-ai.jpgwww.uva.nl/binaries/_ht_17767648366... https://www.uva.nl/binaries/_ht_1776764836666/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/vooroordelen-en-ai.jpg — 200 — 41.9 KiB — 54 ms — h2https://www.uva.nl/binaries/_ht_1776352587422/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/nieuws/2026/003uvabezoekamaliasciencepark.jpgwww.uva.nl/binaries/_ht_17763525874... https://www.uva.nl/binaries/_ht_1776352587422/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/nieuws/2026/003uvabezoekamaliasciencepark.jpg — 200 — 38.5 KiB — 59 ms — h2https://www.uva.nl/binaries/_ht_1776259396361/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/meet-the-professor-2025.jpgwww.uva.nl/binaries/_ht_17762593963... https://www.uva.nl/binaries/_ht_1776259396361/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/meet-the-professor-2025.jpg — 200 — 120.2 KiB — 72 ms — h2https://www.uva.nl/binaries/_ht_1775634045766/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/drawing-for-television-cover.jpgwww.uva.nl/binaries/_ht_17756340457... https://www.uva.nl/binaries/_ht_1775634045766/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/drawing-for-television-cover.jpg — 200 — 29.7 KiB — 65 ms — h2https://www.uva.nl/binaries/_ht_1717664335202/700x0-webp/content/gallery/onderzoek/global-connections.jpgwww.uva.nl/binaries/_ht_17176643352... https://www.uva.nl/binaries/_ht_1717664335202/700x0-webp/content/gallery/onderzoek/global-connections.jpg — 200 — 12.4 KiB — 69 ms — h2https://www.uva.nl/binaries/_ht_1733155541129/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/samenwerking-met-derden/people-celebrating-world-population-day.jpgwww.uva.nl/binaries/_ht_17331555411... https://www.uva.nl/binaries/_ht_1733155541129/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/samenwerking-met-derden/people-celebrating-world-population-day.jpg — 200 — 69.2 KiB — 330 ms — h2https://www.uva.nl/binaries/_ht_1692278887151/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/ozge-idikut.jpgwww.uva.nl/binaries/_ht_16922788871... https://www.uva.nl/binaries/_ht_1692278887151/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/ozge-idikut.jpg — 200 — 21.2 KiB — 1.3 s — h2https://www.uva.nl/binaries/_ht_1683704266392/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/annemarie-maenen.jpgwww.uva.nl/binaries/_ht_16837042663... https://www.uva.nl/binaries/_ht_1683704266392/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/annemarie-maenen.jpg — 200 — 31.9 KiB — 66 ms — h2https://www.uva.nl/binaries/_ht_1692278488642/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/gionello-constansia.jpgwww.uva.nl/binaries/_ht_16922784886... https://www.uva.nl/binaries/_ht_1692278488642/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/gionello-constansia.jpg — 200 — 19.4 KiB — 1.3 s — h2https://use.typekit.net/af/4db8bf/00000000000000007735d61c/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3use.typekit.net/af/4db8bf/000000000... https://use.typekit.net/af/4db8bf/00000000000000007735d61c/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3 — 200 — 43.1 KiB — 20 ms — h2https://use.typekit.net/af/14f0be/000000000000000077586386/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3use.typekit.net/af/14f0be/000000000... https://use.typekit.net/af/14f0be/000000000000000077586386/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3 — 200 — 37.7 KiB — 22 ms — h2
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 1.8 s LCP 2.2 shttps://uva.nl// https://uva.nl/ — 301 — 651 B — 111 ms — h2https://www.uva.nl/www.uva.nl/ https://www.uva.nl/ — 200 — 164.5 KiB — 208 ms — h2https://www.uva.nl/webfiles/1765960941537/css/app.min.csswww.uva.nl/webfiles/1765960941537/c... https://www.uva.nl/webfiles/1765960941537/css/app.min.css — 200 — 359.2 KiB — 135 ms — h2https://www.uva.nl/webfiles/1765960941537/js/uvacookiebar.jswww.uva.nl/webfiles/1765960941537/j... https://www.uva.nl/webfiles/1765960941537/js/uvacookiebar.js — 200 — 3.2 KiB — 100 ms — h2https://www.uva.nl/webfiles/1765960941537/includes/home-research-nl/home-research-nl.csswww.uva.nl/webfiles/1765960941537/i... https://www.uva.nl/webfiles/1765960941537/includes/home-research-nl/home-research-nl.css — 200 — 3.3 KiB — 99 ms — h2https://www.uva.nl/webfiles/1765960941537/includes/home-overdeuva-nl/home-overdeuva-nl.csswww.uva.nl/webfiles/1765960941537/i... https://www.uva.nl/webfiles/1765960941537/includes/home-overdeuva-nl/home-overdeuva-nl.css — 200 — 2.9 KiB — 99 ms — h2https://www.uva.nl/webfiles/1765960941537/_favicon/manifest.jsonwww.uva.nl/webfiles/1765960941537/_... https://www.uva.nl/webfiles/1765960941537/_favicon/manifest.json — 200 — 1.4 KiB — 123 ms — h2https://www.uva.nl/webfiles/1765960941537/js/app.jswww.uva.nl/webfiles/1765960941537/j... https://www.uva.nl/webfiles/1765960941537/js/app.js — 200 — 295.0 KiB — 78 ms — h2https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/MathJax.js?config=TeX-AMS_HTMLcdnjs.cloudflare.com/ajax/libs/math... https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/MathJax.js?config=TeX-AMS_HTML — 200 — 17.3 KiB — 67 ms — h3https://www.googletagmanager.com/gtm.js?id=GTM-HX98www.googletagmanager.com/gtm.js?id=... https://www.googletagmanager.com/gtm.js?id=GTM-HX98 — 200 — 197.7 KiB — 182 ms — h2https://use.typekit.net/emf5eij.cssuse.typekit.net/emf5eij.css https://use.typekit.net/emf5eij.css — 200 — 1.2 KiB — 9 ms — h2https://www.uva.nl/webfiles/1765960941537/css/print.min.csswww.uva.nl/webfiles/1765960941537/c... https://www.uva.nl/webfiles/1765960941537/css/print.min.css — 200 — 5.8 KiB — 40 ms — h2https://p.typekit.net/p.css?s=1&k=emf5eij&ht=tk&f=13378.13379.13380.13381.13382.13383.17265.17270.17272&a=13802896&app=typekit&e=cssp.typekit.net/p.css?s=1&k=emf5eij&h... https://p.typekit.net/p.css?s=1&k=emf5eij&ht=tk&f=13378.13379.13380.13381.13382.13383.17265.17270.17272&a=13802896&app=typekit&e=css — 200 — 172 B — 16 ms — h2https://analytics.ic.uva.nl/matomo.jsanalytics.ic.uva.nl/matomo.js https://analytics.ic.uva.nl/matomo.js — 200 — 66.7 KiB — 194 ms — http/1.1https://www.uva.nl/webfiles/1765960941537/icons/svg-logos.svgwww.uva.nl/webfiles/1765960941537/i... https://www.uva.nl/webfiles/1765960941537/icons/svg-logos.svg — 200 — 69.6 KiB — 40 ms — h2data:image/svg+xml;charset=utf8, %3Csvg height='20' viewBox='0 0 20 20' width='20' xmlns='http://ww…ww… data:image/svg+xml;charset=utf8, %3Csvg height='20' viewBox='0 0 20 20' width='20' xmlns='http://ww… — 200 — 0 B — 0 ms — datadata:image/svg+xml;charset=utf8, %3Csvg xmlns='http://www.w3.org/2000/svg' height='100' viewBox='0 …www.w3.org/2000/svg' height='100' v... data:image/svg+xml;charset=utf8, %3Csvg xmlns='http://www.w3.org/2000/svg' height='100' viewBox='0 … — 200 — 0 B — 0 ms — datahttps://www.uva.nl/binaries/_ht_1744634291608/1400x700-webp/content/gallery/evenementen/2025/minorweek/202504-kies-je-minor.pngwww.uva.nl/binaries/_ht_17446342916... https://www.uva.nl/binaries/_ht_1744634291608/1400x700-webp/content/gallery/evenementen/2025/minorweek/202504-kies-je-minor.png — 200 — 39.7 KiB — 58 ms — h2https://www.uva.nl/webfiles/1765960941537/includes/home-research-nl/img/seven-klimaatinitiatief-Still.pngwww.uva.nl/webfiles/1765960941537/i... https://www.uva.nl/webfiles/1765960941537/includes/home-research-nl/img/seven-klimaatinitiatief-Still.png — 200 — 294.1 KiB — 70 ms — h2https://www.uva.nl/binaries/_ht_1776764836666/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/vooroordelen-en-ai.jpgwww.uva.nl/binaries/_ht_17767648366... https://www.uva.nl/binaries/_ht_1776764836666/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/vooroordelen-en-ai.jpg — 200 — 41.9 KiB — 54 ms — h2https://www.uva.nl/binaries/_ht_1776352587422/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/nieuws/2026/003uvabezoekamaliasciencepark.jpgwww.uva.nl/binaries/_ht_17763525874... https://www.uva.nl/binaries/_ht_1776352587422/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/nieuws/2026/003uvabezoekamaliasciencepark.jpg — 200 — 38.5 KiB — 59 ms — h2https://www.uva.nl/binaries/_ht_1776259396361/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/meet-the-professor-2025.jpgwww.uva.nl/binaries/_ht_17762593963... https://www.uva.nl/binaries/_ht_1776259396361/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/meet-the-professor-2025.jpg — 200 — 120.2 KiB — 72 ms — h2https://www.uva.nl/binaries/_ht_1775634045766/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/drawing-for-television-cover.jpgwww.uva.nl/binaries/_ht_17756340457... https://www.uva.nl/binaries/_ht_1775634045766/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/drawing-for-television-cover.jpg — 200 — 29.7 KiB — 65 ms — h2https://www.uva.nl/binaries/_ht_1717664335202/700x0-webp/content/gallery/onderzoek/global-connections.jpgwww.uva.nl/binaries/_ht_17176643352... https://www.uva.nl/binaries/_ht_1717664335202/700x0-webp/content/gallery/onderzoek/global-connections.jpg — 200 — 12.4 KiB — 69 ms — h2https://www.uva.nl/binaries/_ht_1733155541129/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/samenwerking-met-derden/people-celebrating-world-population-day.jpgwww.uva.nl/binaries/_ht_17331555411... https://www.uva.nl/binaries/_ht_1733155541129/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/samenwerking-met-derden/people-celebrating-world-population-day.jpg — 200 — 69.2 KiB — 330 ms — h2https://www.uva.nl/binaries/_ht_1692278887151/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/ozge-idikut.jpgwww.uva.nl/binaries/_ht_16922788871... https://www.uva.nl/binaries/_ht_1692278887151/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/ozge-idikut.jpg — 200 — 21.2 KiB — 1.3 s — h2https://www.uva.nl/binaries/_ht_1683704266392/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/annemarie-maenen.jpgwww.uva.nl/binaries/_ht_16837042663... https://www.uva.nl/binaries/_ht_1683704266392/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/annemarie-maenen.jpg — 200 — 31.9 KiB — 66 ms — h2https://www.uva.nl/binaries/_ht_1692278488642/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/gionello-constansia.jpgwww.uva.nl/binaries/_ht_16922784886... https://www.uva.nl/binaries/_ht_1692278488642/700x0-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/werken-bij-de-uva/gionello-constansia.jpg — 200 — 19.4 KiB — 1.3 s — h2https://use.typekit.net/af/4db8bf/00000000000000007735d61c/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3use.typekit.net/af/4db8bf/000000000... https://use.typekit.net/af/4db8bf/00000000000000007735d61c/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3 — 200 — 43.1 KiB — 20 ms — h2https://use.typekit.net/af/14f0be/000000000000000077586386/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3use.typekit.net/af/14f0be/000000000... https://use.typekit.net/af/14f0be/000000000000000077586386/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n4&v=3 — 200 — 37.7 KiB — 22 ms — h2https://use.typekit.net/af/642cd4/000000000000000077587094/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n6&v=3use.typekit.net/af/642cd4/000000000... https://use.typekit.net/af/642cd4/000000000000000077587094/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n6&v=3 — 200 — 38.0 KiB — 22 ms — h2https://use.typekit.net/af/4f35a4/00000000000000007735d633/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n6&v=3use.typekit.net/af/4f35a4/000000000... https://use.typekit.net/af/4f35a4/00000000000000007735d633/31/l?primer=7cdcb44be4a7db8877ffa5c0007b8dd865b3bbc383831fe2ea177f62257a9191&fvd=n6&v=3 — 200 — 43.7 KiB — 23 ms — h2https://www.uva.nl/webfiles/1765960941537/js/4.jswww.uva.nl/webfiles/1765960941537/j... https://www.uva.nl/webfiles/1765960941537/js/4.js — 200 — 7.2 KiB — 47 ms — h2https://www.uva.nl/webfiles/1765960941537/js/365.jswww.uva.nl/webfiles/1765960941537/j... https://www.uva.nl/webfiles/1765960941537/js/365.js — 200 — 3.8 KiB — 42 ms — h2https://www.uva.nl/webfiles/1765960941537/js/812.jswww.uva.nl/webfiles/1765960941537/j... https://www.uva.nl/webfiles/1765960941537/js/812.js — 200 — 2.4 KiB — 46 ms — h2https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/config/TeX-AMS_HTML.js?V=2.7.4cdnjs.cloudflare.com/ajax/libs/math... https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/config/TeX-AMS_HTML.js?V=2.7.4 — 200 — 53.7 KiB — 47 ms — h3https://www.uva.nl/webfiles/1765960941537/js/699.jswww.uva.nl/webfiles/1765960941537/j... https://www.uva.nl/webfiles/1765960941537/js/699.js — 200 — 136.9 KiB — 51 ms — h2https://www.uva.nl/binaries/_ht_1775637956093/1400x700-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/pexels-gabby-k-5841764.jpgwww.uva.nl/binaries/_ht_17756379560... https://www.uva.nl/binaries/_ht_1775637956093/1400x700-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/pexels-gabby-k-5841764.jpg — 200 — 13.5 KiB — 44 ms — h2https://www.uva.nl/binaries/_ht_1773327729874/1400x700-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/onderzoekssectie/themapaginas/wereldmacht/hero_v2-2560x1440.jpgwww.uva.nl/binaries/_ht_17733277298... https://www.uva.nl/binaries/_ht_1773327729874/1400x700-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/onderzoekssectie/themapaginas/wereldmacht/hero_v2-2560x1440.jpg — 200 — 135.0 KiB — 47 ms — h2https://www.uva.nl/binaries/_ht_1774453145693/1400x700-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/schimmelpenninck/portret-van-schimmelpenninck.jpgwww.uva.nl/binaries/_ht_17744531456... https://www.uva.nl/binaries/_ht_1774453145693/1400x700-webp/content/gallery/faculteiten-en-diensten/uva-bureau-communicatie/persvoorlichting/2026/schimmelpenninck/portret-van-schimmelpenninck.jpg — 200 — 73.6 KiB — 47 ms — h2https://analytics.ic.uva.nl/matomo.php?action_name=Universiteit%20van%20Amsterdam&idsite=31&rec=1&r=706958&h=21&m=11&s=37&url=https%3A%2F%2Fwww.uva.nl%2F&_id=4c65d9c426a7385b&_idn=1&send_image=0&_refts=0&pv_id=odGLaI&pf_net=0&pf_srv=136&pf_tfr=71&pf_dm1=377&uadata=%7B%22formFactors%22%3A%5B%22Desktop%22%5D%2C%22fullVersionList%22%3A%5B%7B%22brand%22%3A%22Chromium%22%2C%22version%22%3A%22147.0.7727.101%22%7D%2C%7B%22brand%22%3A%22Not.A%2FBrand%22%2C%22version%22%3A%228.0.0.0%22%7D%5D%2C%22mobile%22%3Afalse%2C%22model%22%3A%22%22%2C%22platform%22%3A%22macOS%22%2C%22platformVersion%22%3A%2210.15.7%22%7D&pdf=1&qt=0&realp=0&wma=0&fla=0&java=0&ag=0&cookie=1&res=800x600analytics.ic.uva.nl/matomo.php?acti... https://analytics.ic.uva.nl/matomo.php?action_name=Universiteit%20van%20Amsterdam&idsite=31&rec=1&r=706958&h=21&m=11&s=37&url=https%3A%2F%2Fwww.uva.nl%2F&_id=4c65d9c426a7385b&_idn=1&send_image=0&_refts=0&pv_id=odGLaI&pf_net=0&pf_srv=136&pf_tfr=71&pf_dm1=377&uadata=%7B%22formFactors%22%3A%5B%22Desktop%22%5D%2C%22fullVersionList%22%3A%5B%7B%22brand%22%3A%22Chromium%22%2C%22version%22%3A%22147.0.7727.101%22%7D%2C%7B%22brand%22%3A%22Not.A%2FBrand%22%2C%22version%22%3A%228.0.0.0%22%7D%5D%2C%22mobile%22%3Afalse%2C%22model%22%3A%22%22%2C%22platform%22%3A%22macOS%22%2C%22platformVersion%22%3A%2210.15.7%22%7D&pdf=1&qt=0&realp=0&wma=0&fla=0&java=0&ag=0&cookie=1&res=800x600 — 204 — 281 B — 114 ms — http/1.1https://www.googletagmanager.com/gtag/js?id=G-44XGTNSN28&cx=c&gtm=4e64h1h1www.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-44XGTNSN28&cx=c&gtm=4e64h1h1 — 200 — 169.8 KiB — 42 ms — h2https://siteimproveanalytics.com/js/siteanalyze_6004849.jssiteimproveanalytics.com/js/siteana... https://siteimproveanalytics.com/js/siteanalyze_6004849.js — 200 — 103.9 KiB — 115 ms — h3https://region1.google-analytics.com/g/collect?v=2&tid=G-44XGTNSN28&gtm=45je64h1h1v884170545z8581158za20gzb581158zd581158&_p=1776805897277&gcs=G101&gcd=13q3v3q2q7l1&npa=1&dma_cps=-&dma=1&_eu=EA&_geo=1&_rdi=1&are=1&cid=1851082198.1776805898&frm=0&ir=1&pscdl=denied&rcb=9&ul=en-us&_s=1&tag_exp=0~115938465~115938469~117266400&dl=https%3A%2F%2Fwww.uva.nl%2F&sid=1776805898&sct=1&seg=0&dt=Universiteit%20van%20Amsterdam&_tu=CA&en=page_view&_fv=1&_nsi=1&_ss=1&ep.opleiding_naam=undefined&ep.opleiding_type=undefined&ep.faculteit_naam=undefined&ep.opleiding_croho=undefined&ep.croho_naam=undefined&tfd=1042region1.google-analytics.com/g/coll... https://region1.google-analytics.com/g/collect?v=2&tid=G-44XGTNSN28&gtm=45je64h1h1v884170545z8581158za20gzb581158zd581158&_p=1776805897277&gcs=G101&gcd=13q3v3q2q7l1&npa=1&dma_cps=-&dma=1&_eu=EA&_geo=1&_rdi=1&are=1&cid=1851082198.1776805898&frm=0&ir=1&pscdl=denied&rcb=9&ul=en-us&_s=1&tag_exp=0~115938465~115938469~117266400&dl=https%3A%2F%2Fwww.uva.nl%2F&sid=1776805898&sct=1&seg=0&dt=Universiteit%20van%20Amsterdam&_tu=CA&en=page_view&_fv=1&_nsi=1&_ss=1&ep.opleiding_naam=undefined&ep.opleiding_type=undefined&ep.faculteit_naam=undefined&ep.opleiding_croho=undefined&ep.croho_naam=undefined&tfd=1042 — 204 — 546 B — 65 ms — h2https://www.uva.nl/webfiles/1765960941537/_favicon/favicon.icowww.uva.nl/webfiles/1765960941537/_... https://www.uva.nl/webfiles/1765960941537/_favicon/favicon.ico — 200 — 7.9 KiB — 41 ms — h2https://6004849.global.siteimproveanalytics.io/image.aspx?url=https%3A%2F%2Fwww.uva.nl%2F&title=Universiteit%20van%20Amsterdam&res=800x600&accountid=6004849&rt=1071&prev=88904ec4-d689-08aa-0c2c-4d16a9e05651&luid=dbd691be-673a-5a87-b12c-6b57b8133435&rnd=144936004849.global.siteimproveanalytics... https://6004849.global.siteimproveanalytics.io/image.aspx?url=https%3A%2F%2Fwww.uva.nl%2F&title=Universiteit%20van%20Amsterdam&res=800x600&accountid=6004849&rt=1071&prev=88904ec4-d689-08aa-0c2c-4d16a9e05651&luid=dbd691be-673a-5a87-b12c-6b57b8133435&rnd=14493 — 200 — 210 B — 99 ms — h2https://6004849.global.siteimproveanalytics.io/surveyview.aspx?aid=6004849&url=https%3A%2F%2Fwww.uva.nl%2F&title=Universiteit%20van%20Amsterdam&luid=dbd691be-673a-5a87-b12c-6b57b8133435&prev=88904ec4-d689-08aa-0c2c-4d16a9e05651&feedback_id=18684323682&sluid=b0311fee-56d0-2a58-244b-1b92ff004b52&o=1&rnd=289396004849.global.siteimproveanalytics... https://6004849.global.siteimproveanalytics.io/surveyview.aspx?aid=6004849&url=https%3A%2F%2Fwww.uva.nl%2F&title=Universiteit%20van%20Amsterdam&luid=dbd691be-673a-5a87-b12c-6b57b8133435&prev=88904ec4-d689-08aa-0c2c-4d16a9e05651&feedback_id=18684323682&sluid=b0311fee-56d0-2a58-244b-1b92ff004b52&o=1&rnd=28939 — 200 — 209 B — 99 ms — h2
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 703ms · 931KB · €8/mo
www.uva.nl
Other
Costly
Execution 214ms
Transfer 295 KB
Unused 66%
Monthly Cost €2/mo
www.uva.nl
Other
Optional
Execution 155ms
Transfer 164 KB
Monthly Cost €2/mo
Google Tag Manager
Tag Manager
Optional
Execution 122ms
Transfer 198 KB
Unused 33%
Monthly Cost €1/mo
Google Tag Manager
Tag Manager
Optional
Execution 82ms
Transfer 170 KB
Unused 39%
Monthly Cost €1/mo
Unattributable
Other
Optional
Execution 78ms
Transfer 0 KB
Monthly Cost €1/mo
siteimproveanalytics.com
Other
Optional
Execution 51ms
Transfer 104 KB
Unused 67%
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • www.uva.nl adds 214ms 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.uva.nl takes 214ms 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

66% of www.uva.nl'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

67% of siteimproveanalytics.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.

Send Feedback