Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

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

Mobile Desktop

Performance

Accessibility

100

Best Practices

SEO

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

1.38 s

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

1.68 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.

0.022

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

2.50 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.

1.68 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

12 PASS 2 REVIEW 1 FIX

JS Execution Cost

Action

2440ms total JS execution

FIX

2440ms total JS execution

https://uni-koeln.de/: 1889ms CPU time

Unattributable: 367ms CPU time

https://uni-koeln.de/typo3conf/ext/uzk2025/Resourc...: 132ms CPU time

https://matomo.rrz.uni-koeln.de/matomo.js: 52ms CPU time

Third-party scripts: 419ms (17% of total)

Main Thread Breakdown

Other 34% Style & Layout 31% Rendering 25% Script Evaluation 6% Parse HTML & CSS 3%

Script	Total	Scripting	Parse/Compile	Party
https://uni-koeln.de/	1889ms	39ms	2ms	1st
Unattributable	367ms	20ms	0ms	3rd
https://uni-koeln.de/typo3conf/ext/uzk2025/Resources/Public/Js/animated-news-teaser-BHP9S2X_.js	132ms	23ms	0ms	1st
https://matomo.rrz.uni-koeln.de/matomo.js	52ms	38ms	9ms	3rd

Image Optimization

6 images, 0 KB saveable

REVIEW

6 images, 0 KB saveable

is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

https://uni-koeln.de/sites/uni/_processed_/1/5/csm... is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

6 images 424 KB

0 oversized -0 KB

4 legacy format

2 missing dimensions CLS risk

Set explicit width and height to prevent CLS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

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

Green Hosting

Action

Whether the site is served from green-energy infrastructure

REVIEW

Green Hosting

No green hosting detected

A+

Page Weight Budget

660 KB transferred, 20 requests

PASS

660 KB transferred, 20 requests

Page weighs 1.5 MB (660 KB transferred)

20 HTTP requests

Estimated 0.14 g CO2 per page load

660 KB transferred

20 requests

0.14 g CO2 per page load

Images 423.8 KiB 64%

HTML 60.8 KiB 9%

Other 56.0 KiB 8%

JavaScript 52.9 KiB 8%

CSS 35.1 KiB 5%

Fonts 31.7 KiB 5%

Other 192 B 0%

0 2.4 MB 4.9 MB

Under budget

A+

Third-Party Impact

3% third-party, 0 ms blocking

PASS

3% third-party, 0 ms blocking

Third-party code accounts for 3% of page weight (22.1 KiB of 660.3 KiB)

Third-party blocking time is low (0 ms)

97%

First-party Third-party

A+

Text Compression

All text resources are compressed

PASS

All text resources are compressed

All text resources are properly compressed.

A+

Font Loading

1 fonts (32 KB)

PASS

1 fonts (32 KB)

1 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

32 KB total

Render-blocking

of 1

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

albert-sans-latin-wght-... woff2 swap

Size 32 KB

Load time 168 ms

Start 1.3 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+

JS Bundles

5 scripts, 0 KB unused

PASS

5 scripts, 0 KB unused

0 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://uni-koeln.de/typo3conf/ext/uzk2025/Resources/Public/Js/main-8eAe4pPs.js	5 KB	—	✓	1st
https://uni-koeln.de/typo3conf/ext/powermail/Resources/Public/JavaScript/Powermail/Form.min.js?1753202143	23 KB	—	✓	1st
https://matomo.rrz.uni-koeln.de/matomo.js	22 KB	—	✓	3rd
https://uni-koeln.de/typo3conf/ext/uzk2025/Resources/Public/Js/animated-news-teaser-BHP9S2X_.js	1 KB	—	✓	1st
https://uni-koeln.de/typo3conf/ext/uzk2025/Resources/Public/Js/forms-Du4ZAIZx.js	1 KB	—	✓	1st

A+

Resource Caching

All resources properly cached

PASS

All resources properly cached

No caching issues found

All static resources have appropriate caching headers.

A+

Critical Rendering Path

No render-blocking resources

PASS

No render-blocking resources

No render-blocking resources detected

A+

Resource Hints

No optimization needed

PASS

No optimization needed

No resource hint issues

A+

Page Weight Inventory

20 resources · 660 KB · 0 KB savings available

PASS

20 resources · 660 KB · 0 KB savings available

Within 1MB page-weight target

Got: 660 KB

2 third-party resources (3% of weight)

1 resources over 200KB

20 resources · 660.3 KiB · 2 third-party Within 1MB page-weight target

Image 73% · 479.7 KiB

Document 9% · 61.0 KiB

JavaScript 8% · 52.9 KiB

CSS 5% · 35.1 KiB

Font 5% · 31.7 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

20 resources			660.3 KiB

A+

Render-Blocking Resources

No render-blocking resources detected

PASS

No render-blocking resources detected

No render-blocking resources detected in <head>

A+

Third-Party Resources

No third-party resources detected

PASS

No third-party resources detected

HTTP Caching

max-age=85676 (23 hours)

PASS

max-age=85676 (23 hours)

Cache-Control header is set

Got: max-age=85676

Effective TTL: 23 hours (max-age=85676)

No ETag or Last-Modified header

Conditional requests (304 Not Modified) are not possible without validators.

Cache-Control

max-age=85676

Directive	Value	Meaning
max-age	85676	Cache for 23 hours

Effective TTL: 85676 seconds

Network Waterfall

20 requests over 2525ms

INFO

HTML JavaScript CSS Images Fonts XHR/Fetch Other

Third-Party Script Cost

Per-script blocking time, transfer cost, and cache headers

INFO

17% of JavaScript execution is third-party

First-party Third-party 419ms · 22KB · €5/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
Unattributable Unattributable	Other	367ms	0 KB	—	€4/mo	Costly
Matomo matomo.rrz.uni-koeln.de	Analytics	52ms	22 KB	—	€1/mo	Optional

Unattributable

Other

Costly

Execution 367ms

Transfer 0 KB

Monthly Cost €4/mo

Matomo

Analytics

Optional

Execution 52ms

Transfer 22 KB

Monthly Cost €1/mo

These scripts may cost more than they're worth

Unattributable adds 367ms and costs ~€4/month

Unattributable takes 367ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

Browse & Analyze

Learn

Performance

Page Load Progression

Green Hosting

Font loading timeline

Optimization checklist

These scripts may cost more than they're worth