Performance

· 15 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

100

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.

895 ms

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

1.48 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.

0.058

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

1.68 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.

1.94 s

Page Load Progression

469 ms

938 ms

1.4 s

1.9 s

2.3 s

2.8 s

3.3 s

3.8 s

Checks

6 PASS 3 REVIEW 4 FIX

Page Weight Budget

Action

4.0 MB transferred, 49 requests

FIX

4.0 MB transferred, 49 requests

Page weighs 5.2 MB (4.0 MB transferred)

Images are 1.2 MB — compress or use modern formats

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Got: 1.2 MB

Fonts are 392 KB — consider subsetting or using system fonts

Subset fonts to include only used characters, or switch to system font stacks.

Got: 392 KB

49 HTTP requests

Estimated 0.84 g CO2 per page load

4.0 MB transferred

49 requests

0.84 g CO2 per page load

Other 2.0 MiB 50%

Images 1.2 MiB 31%

Fonts 391.6 KiB 10%

JavaScript 242.1 KiB 6%

CSS 115.7 KiB 3%

HTML 15.1 KiB 0%

Other 2.4 KiB 0%

Other 1.7 KiB 0%

0 2.4 MB 4.9 MB

Over budget

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Why this matters

Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.

Source: web.dev

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

Third-Party Impact

Action

100% third-party, 0 ms blocking

FIX

100% third-party, 0 ms blocking

Third-party code accounts for 100% of page weight (4.0 MiB of 4.0 MiB)

Third-party blocking time is low (0 ms)

100%

First-party Third-party

Page Weight Inventory

Action

49 resources · 4.0 MB · 140 KB savings available

FIX

49 resources · 4.0 MB · 140 KB savings available

Page weight 3.0 MB over 1MB target

Got: 4.0 MB Expected: ≤ 1 MB

~140 KB of savings available

48 third-party resources (100% of weight)

3 resources over 200KB

49 resources · 4.0 MiB · 48 third-party 3.0 MiB over 1MB target

Media 50% · 2.0 MiB

Image 31% · 1.2 MiB

Font 10% · 391.6 KiB

JavaScript 6% · 242.1 KiB

CSS 3% · 115.7 KiB

Document 0% · 15.4 KiB

Other 0% · 1.9 KiB

~139.7 KiB of savings available

Remove unused JavaScript: 139.7 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

49 resources			4.0 MiB

HTTP Caching

Action

No cache headers

FIX

No cache headers

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.

Image Optimization

28 images, 0 KB saveable

REVIEW

28 images, 0 KB saveable

All images are well-optimized

28 images 1.2 MB

0 oversized -0 KB

21 legacy format

0 missing dimensions CLS risk

JS Bundles

5 scripts, 140 KB unused

REVIEW

5 scripts, 140 KB unused

https://assets.rrz.uni-hamburg.de/assets/2-a25a64b...: 140 KB unused (70%)

Consider code splitting or tree shaking to reduce unused code.

Total unused JavaScript: 140 KB

140 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://assets.rrz.uni-hamburg.de/assets/2-a25a64b8ef71e4d939753923135383c905c3d9038fbbae14392eb09165a1bd56.js	200 KB	140 KB (70%)	✓	3rd
https://www.betterweb.uni-hamburg.de/web/rum.js	7 KB	—	✓	3rd
https://code.etracker.com/code/e.js	31 KB	—	✓	3rd
https://code.etracker.com/t.js?v=ee485f6&et=OBVZu9	4 KB	—	✓	3rd
https://www.etracker.de/cntcc?&&et=OBVZu9&v=6.0&tc=17768094528684&pagename=https%3A%2F%2Fwww.uni-hamburg.de%2F&ilevel=1&et_source_url=https%3A%2F%2Fwww.uni-hamburg.de%2F&cc_ordercurr=EUR&cc_ordertype=lead&cc_baskettype=basket&block_cookies=true&respect_dnt=true&et_bs=1&code_source=%2F%2Fcode.etracker.com%2Fcode%2Fe.js&code_async=true&page_id=809452639&et_sbscr=0&coid=b3f7f878ec4a1cf341eaf9f043f30d72&et_cblk=1&et_cd=www.uni-hamburg.de&dh=YoFjh86e0p3ap4OKeGhaxEHptcUxgg0P&clt=24	0 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

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

All text resources are properly compressed.

A+

JS Execution Cost

390ms total JS execution

PASS

390ms total JS execution

https://assets.rrz.uni-hamburg.de/assets/2-a25a64b...: 177ms CPU time

Unattributable: 131ms CPU time

https://www.uni-hamburg.de/: 82ms CPU time

Third-party scripts: 390ms (100% of total)

Main Thread Breakdown

Other 33% Script Evaluation 31% Style & Layout 24% Script Parsing & Compilation 4% Rendering 4% Parse HTML & CSS 3%

Script	Total	Scripting	Parse/Compile	Party
https://assets.rrz.uni-hamburg.de/assets/2-a25a64b8ef71e4d939753923135383c905c3d9038fbbae14392eb09165a1bd56.js	177ms	99ms	14ms	3rd
Unattributable	131ms	3ms	0ms	3rd
https://www.uni-hamburg.de/	82ms	5ms	1ms	3rd

A+

Font Loading

6 fonts (392 KB)

PASS

6 fonts (392 KB)

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

Web fonts

392 KB total

Render-blocking

of 6

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

TheSansUHHSemiLightCaps... woff2 swap

Size 27 KB

Load time 243 ms

Start 678 ms