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https://fu-berlin.de

Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
84
GRADE
B
FIX
2
REVIEW
5
PASS
6
INFO
2

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

Mobile Desktop
97
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.
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.

816 ms

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

1.14 s

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

0 ms

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

0.010

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

1.16 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.

1.14 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 5 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 (1.4 MiB of 1.4 MiB)
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.

B
Page Weight Budget
1.4 MB transferred, 27 requests
REVIEW
1.4 MB transferred, 27 requests
Info::
Page weighs 2.1 MB (1.4 MB transferred)
Info::
Fonts are 293 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 293 KB
Info::
27 HTTP requests
Info::
Estimated 0.29 g CO2 per page load
1.4 MB / 2.4 MB budget
1.4 MB transferred
27 requests
0.29 g CO2 per page load
Images 889.7 KiB 64%
Fonts 292.5 KiB 21%
JavaScript 130.4 KiB 9%
CSS 50.3 KiB 4%
Other 15.9 KiB 1%
HTML 12.1 KiB 1%
Other 2.2 KiB 0%
0 2.4 MB 4.9 MB
Under budget

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

C
Image Optimization
Action
13 images, 0 KB saveable
REVIEW
13 images, 0 KB saveable
Warning::
https://www.fu-berlin.de/campusleben/forschen/2026... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/_inhalte/forschen_bcp.jpg... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/_inhalte/banner/banner_fa... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/_inhalte/banner/bua-logo-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/_inhalte/banner/systemakk... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/_inhalte/banner/una-europ... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/_inhalte/studium_puk.jpg?... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/sites/startseite-test/inh... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/_inhalte/banner/german-u1... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/assets/default2/fu-siegel... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/_campus-aktuell/_fotos-gr... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.fu-berlin.de/_campus-aktuell/_fotos-gr... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
13 images 890 KB
0 oversized -0 KB
13 legacy format
12 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

B
JS Bundles
2 scripts, 78 KB unused
REVIEW
2 scripts, 78 KB unused
Warning::
https://www.fu-berlin.de/assets/default2/applicati...: 78 KB unused (64%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 78 KB
78 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.fu-berlin.de/assets/default2/application-781670a880dd5cd1754f30fcf22929cb.js122 KB78 KB (64%)✓3rd
https://www.fu-berlin.de/assets/default2/henry-55a2f6b1df7f8729fca2d550689240e9.js8 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

C
Page Weight Inventory
Action
27 resources · 1.4 MB · 78 KB savings available
REVIEW
27 resources · 1.4 MB · 78 KB savings available
Warning::
Page weight 369 KB over 1MB target
Got: 1.4 MB Expected: ≤ 1 MB
Info::
~78 KB of savings available
Warning::
26 third-party resources (100% of weight)
Info::
2 resources over 200KB
27 resources · 1.4 MiB · 26 third-party 369.1 KiB over 1MB target
Image 64% · 891.6 KiB
Font 21% · 292.5 KiB
JavaScript 9% · 130.4 KiB
CSS 4% · 50.3 KiB
Document 2% · 28.2 KiB

~78.0 KiB of savings available

Remove unused JavaScript: 78.0 KiB
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+
JS Execution Cost
156ms total JS execution
PASS
156ms total JS execution
Info::
https://www.fu-berlin.de/: 80ms CPU time
Info::
https://www.fu-berlin.de/assets/default2/applicati...: 76ms CPU time
Warning::
Third-party scripts: 156ms (100% of total)

Main Thread Breakdown

Other 30% Style & Layout 29% Script Evaluation 22% Rendering 8% Parse HTML & CSS 6% Script Parsing & Compilation 4%
ScriptTotalScriptingParse/CompileParty
https://www.fu-berlin.de/80ms1ms0ms3rd
https://www.fu-berlin.de/assets/default2/application-781670a880dd5cd1754f30fcf22929cb.js76ms42ms8ms3rd
A+
Font Loading
4 fonts (293 KB)
PASS
4 fonts (293 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

293 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 FCP 816 ms LCP 1.1 shttps://www.fu-berlin.de/assets/default2/SourceSansPro-Regular.ttf.woffSourceSansPro-Regular.t... https://www.fu-berlin.de/assets/default2/SourceSansPro-Regular.ttf.woff — 116.6 KiB — 43 ms — font-display: swaphttps://www.fu-berlin.de/assets/default2/fontawesome-webfont.woff?v=4.0.1fontawesome-webfont.woff https://www.fu-berlin.de/assets/default2/fontawesome-webfont.woff?v=4.0.1 — 43.7 KiB — 150 ms — font-display: swaphttps://www.fu-berlin.de/assets/default2/SourceSansPro-Semibold.ttf.woffSourceSansPro-Semibold.... https://www.fu-berlin.de/assets/default2/SourceSansPro-Semibold.ttf.woff — 115.9 KiB — 84 ms — font-display: swaphttps://www.fu-berlin.de/assets/default2/cds-ico.woffcds-ico.woff https://www.fu-berlin.de/assets/default2/cds-ico.woff — 16.3 KiB — 40 ms — font-display: swap
SourceSansPro-Regular.t... woff swap
Size 117 KB
Load time 43 ms
Start 988 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
fontawesome-webfont.woff woff swap
Size 44 KB
Load time 150 ms
Start 989 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
SourceSansPro-Semibold.... woff swap
Size 116 KB
Load time 84 ms
Start 989 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
cds-ico.woff woff swap
Size 16 KB
Load time 40 ms
Start 1.2 s
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
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 ~204 KB and ~408 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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
Network Waterfall
27 requests over 1401ms
INFO
0 ms 500 ms 1.0 s FCP 816 ms LCP 1.1 shttps://fu-berlin.de// https://fu-berlin.de/ — 301 — 246 B — 148 ms — http/1.1https://www.fu-berlin.de/www.fu-berlin.de/ https://www.fu-berlin.de/ — 200 — 12.1 KiB — 538 ms — http/1.1https://www.fu-berlin.de/assets/default2/fu-berlin_application-part-1-841e7928a8.csswww.fu-berlin.de/assets/default2/fu... https://www.fu-berlin.de/assets/default2/fu-berlin_application-part-1-841e7928a8.css — 200 — 9.9 KiB — 39 ms — http/1.1https://www.fu-berlin.de/assets/default2/fu-berlin_application-part-2-f043bbb02b.csswww.fu-berlin.de/assets/default2/fu... https://www.fu-berlin.de/assets/default2/fu-berlin_application-part-2-f043bbb02b.css — 200 — 40.4 KiB — 127 ms — http/1.1https://www.fu-berlin.de/assets/default2/application-781670a880dd5cd1754f30fcf22929cb.jswww.fu-berlin.de/assets/default2/ap... https://www.fu-berlin.de/assets/default2/application-781670a880dd5cd1754f30fcf22929cb.js — 200 — 122.4 KiB — 219 ms — http/1.1https://www.fu-berlin.de/assets/default2/spinner-39a0a2170912fd2acf310826322141db.gifwww.fu-berlin.de/assets/default2/sp... https://www.fu-berlin.de/assets/default2/spinner-39a0a2170912fd2acf310826322141db.gif — 200 — 2.1 KiB — 107 ms — http/1.1https://www.fu-berlin.de/_campus-aktuell/_fotos-grafiken/kirschbluete-2026.jpg?width=2000www.fu-berlin.de/_campus-aktuell/_f... https://www.fu-berlin.de/_campus-aktuell/_fotos-grafiken/kirschbluete-2026.jpg?width=2000 — 200 — 244.0 KiB — 288 ms — http/1.1https://www.fu-berlin.de/_campus-aktuell/_fotos-grafiken/fup-26-045-keilschrift.png?width=500www.fu-berlin.de/_campus-aktuell/_f... https://www.fu-berlin.de/_campus-aktuell/_fotos-grafiken/fup-26-045-keilschrift.png?width=500 — 200 — 17.4 KiB — 113 ms — http/1.1https://www.fu-berlin.de/campusleben/forschen/2026/260413-BUA-ACEM-Day-SupraFAB/kai-ludwig-credit-bernd-wannenmacher.jpeg?width=500www.fu-berlin.de/campusleben/forsch... https://www.fu-berlin.de/campusleben/forschen/2026/260413-BUA-ACEM-Day-SupraFAB/kai-ludwig-credit-bernd-wannenmacher.jpeg?width=500 — 200 — 29.0 KiB — 194 ms — http/1.1https://www.fu-berlin.de/assets/default2/henry-55a2f6b1df7f8729fca2d550689240e9.jswww.fu-berlin.de/assets/default2/he... https://www.fu-berlin.de/assets/default2/henry-55a2f6b1df7f8729fca2d550689240e9.js — 200 — 8.0 KiB — 39 ms — http/1.1https://www.fu-berlin.de/_inhalte/studium_puk.jpg?width=1300www.fu-berlin.de/_inhalte/studium_p... https://www.fu-berlin.de/_inhalte/studium_puk.jpg?width=1300 — 200 — 93.6 KiB — 92 ms — http/1.1https://www.fu-berlin.de/_inhalte/forschen_bcp.jpg?width=1300www.fu-berlin.de/_inhalte/forschen_... https://www.fu-berlin.de/_inhalte/forschen_bcp.jpg?width=1300 — 200 — 120.5 KiB — 301 ms — http/1.1https://www.fu-berlin.de/sites/startseite-test/inhalte/intl-menschen.jpg?width=1300www.fu-berlin.de/sites/startseite-t... https://www.fu-berlin.de/sites/startseite-test/inhalte/intl-menschen.jpg?width=1300 — 200 — 268.0 KiB — 238 ms — http/1.1https://www.fu-berlin.de/_inhalte/banner/banner_familiengerechte-hochschule-rd-sw.png?width=500www.fu-berlin.de/_inhalte/banner/ba... https://www.fu-berlin.de/_inhalte/banner/banner_familiengerechte-hochschule-rd-sw.png?width=500 — 200 — 13.5 KiB — 189 ms — http/1.1https://www.fu-berlin.de/assets/default2/SourceSansPro-Regular.ttf.woffwww.fu-berlin.de/assets/default2/So... https://www.fu-berlin.de/assets/default2/SourceSansPro-Regular.ttf.woff — 200 — 116.6 KiB — 43 ms — http/1.1https://www.fu-berlin.de/assets/default2/fontawesome-webfont.woff?v=4.0.1www.fu-berlin.de/assets/default2/fo... https://www.fu-berlin.de/assets/default2/fontawesome-webfont.woff?v=4.0.1 — 200 — 43.7 KiB — 150 ms — http/1.1https://www.fu-berlin.de/assets/default2/SourceSansPro-Semibold.ttf.woffwww.fu-berlin.de/assets/default2/So... https://www.fu-berlin.de/assets/default2/SourceSansPro-Semibold.ttf.woff — 200 — 115.9 KiB — 84 ms — http/1.1https://www.fu-berlin.de/redaktion/direktzugang/index.html?comp=direct_access&irq=1www.fu-berlin.de/redaktion/direktzu... https://www.fu-berlin.de/redaktion/direktzugang/index.html?comp=direct_access&irq=1 — 200 — 2.1 KiB — 101 ms — http/1.1https://www.fu-berlin.de/index.html?comp=navbar&irq=1&pm=0www.fu-berlin.de/index.html?comp=na... https://www.fu-berlin.de/index.html?comp=navbar&irq=1&pm=0 — 200 — 12.6 KiB — 114 ms — http/1.1https://www.fu-berlin.de/kalender/terminuebersicht/index.html?irq=1&page=1www.fu-berlin.de/kalender/terminueb... https://www.fu-berlin.de/kalender/terminuebersicht/index.html?irq=1&page=1 — 200 — 1.2 KiB — 148 ms — http/1.1https://www.fu-berlin.de/_inhalte/banner/bua-logo-banner-sw.png?width=500www.fu-berlin.de/_inhalte/banner/bu... https://www.fu-berlin.de/_inhalte/banner/bua-logo-banner-sw.png?width=500 — 200 — 12.6 KiB — 156 ms — http/1.1https://www.fu-berlin.de/_inhalte/banner/german-u15-logo-rd-sw.png?width=500www.fu-berlin.de/_inhalte/banner/ge... https://www.fu-berlin.de/_inhalte/banner/german-u15-logo-rd-sw.png?width=500 — 200 — 10.3 KiB — 63 ms — http/1.1https://www.fu-berlin.de/_inhalte/banner/systemakkreditierung-siegel-rd-sw.png?width=500www.fu-berlin.de/_inhalte/banner/sy... https://www.fu-berlin.de/_inhalte/banner/systemakkreditierung-siegel-rd-sw.png?width=500 — 200 — 18.2 KiB — 194 ms — http/1.1https://www.fu-berlin.de/assets/default2/cds-ico.woffwww.fu-berlin.de/assets/default2/cd... https://www.fu-berlin.de/assets/default2/cds-ico.woff — 200 — 16.3 KiB — 40 ms — http/1.1https://www.fu-berlin.de/_inhalte/banner/una-europa-logo-banner.png?width=500www.fu-berlin.de/_inhalte/banner/un... https://www.fu-berlin.de/_inhalte/banner/una-europa-logo-banner.png?width=500 — 200 — 14.5 KiB — 48 ms — http/1.1https://www.fu-berlin.de/assets/default2/fu-siegel-web-schwarz-684a4d11be3c3400d8906a344a77c9a4.pngwww.fu-berlin.de/assets/default2/fu... https://www.fu-berlin.de/assets/default2/fu-siegel-web-schwarz-684a4d11be3c3400d8906a344a77c9a4.png — 200 — 45.8 KiB — 38 ms — http/1.1https://www.fu-berlin.de/assets/default2/favicon-12a6f1b0e53f527326498a6bfd4c3abd.icowww.fu-berlin.de/assets/default2/fa... https://www.fu-berlin.de/assets/default2/favicon-12a6f1b0e53f527326498a6bfd4c3abd.ico — 200 — 1.9 KiB — 37 ms — http/1.1
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 156ms · 135KB · €2/mo
www.fu-berlin.de
Other
Optional
Execution 80ms
Transfer 12 KB
Monthly Cost €1/mo
www.fu-berlin.de
Other
Optional
Execution 76ms
Transfer 122 KB
Unused 64%
Monthly Cost €1/mo

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

64% of www.fu-berlin.de'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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