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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
77
GRADE
C
FIX
5
REVIEW
3
PASS
7
INFO
2

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

Mobile Desktop
58
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
97
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.
83
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.

3.87 s

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

6.25 s

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

242 ms

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

0.146

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

4.35 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.

11.02 s

Page Load Progression

404 ms
807 ms
1.2 s
1.6 s
2.0 s
2.4 s
2.8 s
3.2 s
Checks
17
7 PASS 3 REVIEW 5 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 (1.7 MiB of 1.7 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
D
JS Execution Cost
Action
2246ms total JS execution
FIX
2246ms total JS execution
Warning::
https://www.epfl.ch/en/: 749ms CPU time
Warning::
Unattributable: 570ms CPU time
Warning::
https://www.googletagmanager.com/gtag/js?id=G-N6BF...: 291ms CPU time
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-PJG...: 258ms CPU time
Info::
https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7....: 129ms CPU time
Warning::
Third-party scripts: 2246ms (100% of total)

Main Thread Breakdown

Script Evaluation 32% Other 28% Style & Layout 16% Script Parsing & Compilation 8% Parse HTML & CSS 7% Rendering 7%
ScriptTotalScriptingParse/CompileParty
https://www.epfl.ch/en/749ms11ms5ms3rd
Unattributable570ms9ms0ms3rd
https://www.googletagmanager.com/gtag/js?id=G-N6BF9H5G73&cx=c&gtm=4e64h1291ms235ms53ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-PJGBG5R258ms213ms43ms3rd
https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.1/jquery.min.js?ver=1776380526129ms70ms9ms3rd
https://www.epfl.ch/wp-includes/js/jquery/jquery.js?ver=3.7.1106ms52ms43ms3rd
https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/js/vendors.min.js?ver=177638052683ms53ms29ms3rd
https://www.epfl.ch/wp-includes/js/wp-emoji.js?ver=6.9.459ms56ms1ms3rd
D
JS Bundles
Action
13 scripts, 248 KB unused
FIX
13 scripts, 248 KB unused
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-PJG...: 65 KB unused (48%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.epfl.ch/wp-content/themes/wp-theme-201...: 65 KB unused (82%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-N6BF...: 63 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.epfl.ch/wp-includes/js/jquery/jquery.j...: 56 KB unused (67%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.epfl.ch/wp-includes/js/jquery/jquery.j...: unminified — 43 KB could be saved
Info::
Total unused JavaScript: 248 KB
248 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtm.js?id=GTM-PJGBG5R135 KB65 KB (48%)✓3rd
https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/js/vendors.min.js?ver=177638052680 KB65 KB (82%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-N6BF9H5G73&cx=c&gtm=4e64h1149 KB63 KB (42%)✓3rd
https://www.epfl.ch/wp-includes/js/jquery/jquery.js?ver=3.7.185 KB56 KB (67%)✗3rd
https://www.epfl.ch/wp-content/plugins/flowpaper-lite-pdf-flipbook/assets/lity/lity.min.js4 KB—✓3rd
https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.1/jquery.min.js?ver=177638052627 KB—✓3rd
https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/js/elements.min.js?ver=177638052621 KB—✓3rd
https://umami.fsd.epfl.ch/script.js2 KB—✓3rd
https://www.epfl.ch/wp-content/plugins/wp-gutenberg-epfl/frontend/lib/list.min.js?ver=1.57 KB—✓3rd
https://www.epfl.ch/wp-includes/js/jquery/jquery-migrate.js?ver=3.4.111 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

D
Page Weight Inventory
Action
51 resources · 1.7 MB · 248 KB savings available
FIX
51 resources · 1.7 MB · 248 KB savings available
Warning::
Page weight 728 KB over 1MB target
Got: 1.7 MB Expected: ≤ 1 MB
Info::
~248 KB of savings available
Warning::
50 third-party resources (100% of weight)
Info::
2 resources over 200KB
51 resources · 1.7 MiB · 50 third-party 727.6 KiB over 1MB target
Image 62% · 1.1 MiB
JavaScript 31% · 536.5 KiB
CSS 4% · 75.7 KiB
Font 2% · 36.2 KiB
Document 1% · 20.3 KiB
Other 0% · 2.6 KiB

~248.3 KiB of savings available

Remove unused JavaScript: 248.3 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.

C
Page Weight Budget
Action
1.7 MB transferred, 51 requests
REVIEW
1.7 MB transferred, 51 requests
Info::
Page weighs 3.3 MB (1.7 MB transferred)
Warning::
JavaScript is 537 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 537 KB
Info::
51 HTTP requests
Info::
Estimated 0.36 g CO2 per page load
1.7 MB / 2.4 MB budget
1.7 MB transferred
51 requests
0.36 g CO2 per page load
Images 1004.4 KiB 57%
JavaScript 536.5 KiB 31%
CSS 75.7 KiB 4%
Other 74.0 KiB 4%
Fonts 36.2 KiB 2%
HTML 18.4 KiB 1%
Other 3.8 KiB 0%
Other 1.4 KiB 0%
Other 1.3 KiB 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Approaching limit

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

C
Image Optimization
Action
20 images, 0 KB saveable
REVIEW
20 images, 0 KB saveable
Warning::
https://www.epfl.ch/wp-content/uploads/2021/09/Cam... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://memento.epfl.ch/image/32754/509x286.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://memento.epfl.ch/image/32071/509x286.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.epfl.ch/wp-content/uploads/2021/09/Edu... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.epfl.ch/wp-content/uploads/2025/03/EPF... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://memento.epfl.ch/image/32144/509x286.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.epfl.ch/wp-content/themes/wp-theme-201... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.epfl.ch/wp-content/uploads/2021/09/Fac... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://memento.epfl.ch/image/32730/509x286.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://memento.epfl.ch/image/32970/509x286.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.epfl.ch/wp-content/uploads/2021/09/Rec... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://actu.epfl.ch/image/163596/1440x810.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.epfl.ch/wp-content/uploads/2021/09/Inn... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.epfl.ch/wp-content/uploads/2022/12/EPF... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
20 images 1004 KB
0 oversized -0 KB
19 legacy format
14 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

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
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+
Font Loading
2 fonts (36 KB)
PASS
2 fonts (36 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

36 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 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s FCP 3.9 s LCP 6.2 shttps://www.epfl.ch/fonts/SuisseIntl-Regular-WebS.woff2SuisseIntl-Regular-WebS... https://www.epfl.ch/fonts/SuisseIntl-Regular-WebS.woff2 — 17.9 KiB — 27 ms — font-display: swaphttps://www.epfl.ch/fonts/SuisseIntl-SemiBold-WebS.woff2SuisseIntl-SemiBold-Web... https://www.epfl.ch/fonts/SuisseIntl-SemiBold-WebS.woff2 — 18.3 KiB — 26 ms — font-display: swap
SuisseIntl-Regular-WebS... woff2 swap
Size 18 KB
Load time 27 ms
Start 1.4 s
Risk FOUT — text flashes from fallback to web font
SuisseIntl-SemiBold-Web... woff2 swap
Size 18 KB
Load time 26 ms
Start 1.4 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)
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
1 hints, 0 missing preconnects
PASS
1 hints, 0 missing preconnects
Info::
Page uses 1 resource hint(s)

Current Resource Hints

preconnect
—
preload
—
dns-prefetch
1
prefetch
—

1 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
Network Waterfall
51 requests over 3494ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s FCP 3.9 s LCP 6.2 shttps://epfl.ch// https://epfl.ch/ — 301 — 238 B — 789 ms — h2https://www.epfl.ch/www.epfl.ch/ https://www.epfl.ch/ — 302 — 1.7 KiB — 329 ms — h2https://www.epfl.ch/en/www.epfl.ch/en/ https://www.epfl.ch/en/ — 200 — 18.4 KiB — 19 ms — h2https://www.epfl.ch/wp-content/plugins/wp-gutenberg-epfl/build/style-index.css?ver=1776380665www.epfl.ch/wp-content/plugins/wp-g... https://www.epfl.ch/wp-content/plugins/wp-gutenberg-epfl/build/style-index.css?ver=1776380665 — 200 — 2.1 KiB — 67 ms — h3https://www.epfl.ch/wp-content/themes/wp-theme-2018/style.css?ver=1776380526www.epfl.ch/wp-content/themes/wp-th... https://www.epfl.ch/wp-content/themes/wp-theme-2018/style.css?ver=1776380526 — 200 — 1.4 KiB — 35 ms — h3https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/css/vendors.min.css?ver=1776380526www.epfl.ch/wp-content/themes/wp-th... https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/css/vendors.min.css?ver=1776380526 — 200 — 7.7 KiB — 49 ms — h3https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/css/elements.min.css?ver=1776380526www.epfl.ch/wp-content/themes/wp-th... https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/css/elements.min.css?ver=1776380526 — 200 — 52.3 KiB — 73 ms — h3https://www.epfl.ch/wp-content/themes/wp-theme-2018/theme/style.min.css?ver=1776380526www.epfl.ch/wp-content/themes/wp-th... https://www.epfl.ch/wp-content/themes/wp-theme-2018/theme/style.min.css?ver=1776380526 — 200 — 2.0 KiB — 38 ms — h3https://www.epfl.ch/wp-content/plugins/enlighter/cache/enlighterjs.min.css?ver=nOru9GX9Bgee7Xgwww.epfl.ch/wp-content/plugins/enli... https://www.epfl.ch/wp-content/plugins/enlighter/cache/enlighterjs.min.css?ver=nOru9GX9Bgee7Xg — 200 — 10.2 KiB — 58 ms — h3https://www.epfl.ch/wp-includes/js/jquery/jquery.js?ver=3.7.1www.epfl.ch/wp-includes/js/jquery/j... https://www.epfl.ch/wp-includes/js/jquery/jquery.js?ver=3.7.1 — 200 — 84.5 KiB — 74 ms — h3https://www.epfl.ch/wp-includes/js/jquery/jquery-migrate.js?ver=3.4.1www.epfl.ch/wp-includes/js/jquery/j... https://www.epfl.ch/wp-includes/js/jquery/jquery-migrate.js?ver=3.4.1 — 200 — 11.3 KiB — 67 ms — h3https://www.epfl.ch/wp-content/plugins/wp-gutenberg-epfl/frontend/lib/list.min.js?ver=1.5www.epfl.ch/wp-content/plugins/wp-g... https://www.epfl.ch/wp-content/plugins/wp-gutenberg-epfl/frontend/lib/list.min.js?ver=1.5 — 200 — 7.2 KiB — 69 ms — h3https://www.epfl.ch/wp-content/plugins/flowpaper-lite-pdf-flipbook/assets/lity/lity.min.jswww.epfl.ch/wp-content/plugins/flow... https://www.epfl.ch/wp-content/plugins/flowpaper-lite-pdf-flipbook/assets/lity/lity.min.js — 200 — 3.9 KiB — 50 ms — h3https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.1/jquery.min.js?ver=1776380526cdnjs.cloudflare.com/ajax/libs/jque... https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.1/jquery.min.js?ver=1776380526 — 200 — 27.5 KiB — 69 ms — h3https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/svg/epfl-logo.svgwww.epfl.ch/wp-content/themes/wp-th... https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/svg/epfl-logo.svg — 200 — 1.6 KiB — 67 ms — h3https://actu.epfl.ch/image/163596/1440x810.jpgactu.epfl.ch/image/163596/1440x810.... https://actu.epfl.ch/image/163596/1440x810.jpg — 200 — 312.2 KiB — 227 ms — h3https://www.epfl.ch/wp-content/uploads/2026/04/David-Atienza-768x432.jpgwww.epfl.ch/wp-content/uploads/2026... https://www.epfl.ch/wp-content/uploads/2026/04/David-Atienza-768x432.jpg — 200 — 38.7 KiB — 27 ms — h3https://www.epfl.ch/wp-content/uploads/2026/04/Anna-Fontcuberta-i-Morral-768x432.jpgwww.epfl.ch/wp-content/uploads/2026... https://www.epfl.ch/wp-content/uploads/2026/04/Anna-Fontcuberta-i-Morral-768x432.jpg — 200 — 58.9 KiB — 643 ms — h3https://www.epfl.ch/wp-content/uploads/2025/03/EPFL-logo.pngwww.epfl.ch/wp-content/uploads/2025... https://www.epfl.ch/wp-content/uploads/2025/03/EPFL-logo.png — 200 — 1.9 KiB — 25 ms — h3https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/js/vendors.min.js?ver=1776380526www.epfl.ch/wp-content/themes/wp-th... https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/js/vendors.min.js?ver=1776380526 — 200 — 80.3 KiB — 672 ms — h3https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/js/elements.min.js?ver=1776380526www.epfl.ch/wp-content/themes/wp-th... https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/js/elements.min.js?ver=1776380526 — 200 — 21.3 KiB — 44 ms — h3https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/favicons/site.webmanifestwww.epfl.ch/wp-content/themes/wp-th... https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/favicons/site.webmanifest — 200 — 1.3 KiB — 40 ms — h3https://umami.fsd.epfl.ch/script.jsumami.fsd.epfl.ch/script.js https://umami.fsd.epfl.ch/script.js — 200 — 2.0 KiB — 854 ms — h3https://www.epfl.ch/wp-content/uploads/2021/09/Facultes.pngwww.epfl.ch/wp-content/uploads/2021... https://www.epfl.ch/wp-content/uploads/2021/09/Facultes.png — 200 — 4.7 KiB — 668 ms — h3https://www.epfl.ch/wp-content/uploads/2021/09/Campus.pngwww.epfl.ch/wp-content/uploads/2021... https://www.epfl.ch/wp-content/uploads/2021/09/Campus.png — 200 — 3.8 KiB — 29 ms — h3https://memento.epfl.ch/image/32144/509x286.jpgmemento.epfl.ch/image/32144/509x286... https://memento.epfl.ch/image/32144/509x286.jpg — 200 — 31.4 KiB — 214 ms — h3https://memento.epfl.ch/image/32754/509x286.jpgmemento.epfl.ch/image/32754/509x286... https://memento.epfl.ch/image/32754/509x286.jpg — 200 — 36.3 KiB — 217 ms — h3https://memento.epfl.ch/image/32071/509x286.jpgmemento.epfl.ch/image/32071/509x286... https://memento.epfl.ch/image/32071/509x286.jpg — 200 — 28.8 KiB — 1.4 s — h3https://memento.epfl.ch/image/32730/509x286.jpgmemento.epfl.ch/image/32730/509x286... https://memento.epfl.ch/image/32730/509x286.jpg — 200 — 31.1 KiB — 211 ms — h3https://memento.epfl.ch/image/32970/509x286.jpgmemento.epfl.ch/image/32970/509x286... https://memento.epfl.ch/image/32970/509x286.jpg — 200 — 38.7 KiB — 1.1 s — h3
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s FCP 3.9 s LCP 6.2 shttps://epfl.ch// https://epfl.ch/ — 301 — 238 B — 789 ms — h2https://www.epfl.ch/www.epfl.ch/ https://www.epfl.ch/ — 302 — 1.7 KiB — 329 ms — h2https://www.epfl.ch/en/www.epfl.ch/en/ https://www.epfl.ch/en/ — 200 — 18.4 KiB — 19 ms — h2https://www.epfl.ch/wp-content/plugins/wp-gutenberg-epfl/build/style-index.css?ver=1776380665www.epfl.ch/wp-content/plugins/wp-g... https://www.epfl.ch/wp-content/plugins/wp-gutenberg-epfl/build/style-index.css?ver=1776380665 — 200 — 2.1 KiB — 67 ms — h3https://www.epfl.ch/wp-content/themes/wp-theme-2018/style.css?ver=1776380526www.epfl.ch/wp-content/themes/wp-th... https://www.epfl.ch/wp-content/themes/wp-theme-2018/style.css?ver=1776380526 — 200 — 1.4 KiB — 35 ms — h3https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/css/vendors.min.css?ver=1776380526www.epfl.ch/wp-content/themes/wp-th... https://www.epfl.ch/wp-content/themes/wp-theme-2018/assets/css/vendors.min.css?ver=1776380526 — 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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 2246ms · 500KB · CHF11/mo
www.epfl.ch
Other
Costly
Execution 749ms
Transfer 18 KB
Monthly Cost CHF4/mo
Unattributable
Other
Costly
Execution 570ms
Transfer 0 KB
Monthly Cost CHF3/mo
Google Tag Manager
Tag Manager
Costly
Execution 291ms
Transfer 149 KB
Unused 42%
Monthly Cost CHF1/mo
Google Tag Manager
Tag Manager
Costly
Execution 258ms
Transfer 135 KB
Unused 48%
Monthly Cost CHF1/mo
cdnjs
CDN
Optional
Execution 129ms
Transfer 27 KB
Monthly Cost CHF1/mo
www.epfl.ch
Other
Optional
Execution 106ms
Transfer 85 KB
Unused 67%
Monthly Cost CHF1/mo
www.epfl.ch
Other
Optional
Execution 83ms
Transfer 80 KB
Unused 82%
Monthly Cost CHF0/mo
www.epfl.ch
Other
Optional
Execution 59ms
Transfer 4 KB
Monthly Cost CHF0/mo

These scripts may cost more than they're worth

  • www.epfl.ch adds 749ms and costs ~CHF4/month
  • Unattributable adds 570ms and costs ~CHF3/month
  • Google Tag Manager adds 291ms and costs ~CHF1/month
  • Google Tag Manager adds 258ms and costs ~CHF1/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.epfl.ch takes 749ms 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 570ms 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 291ms 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 258ms 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

67% of www.epfl.ch'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

82% of www.epfl.ch'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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