Performance
· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
4.28 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
6.84 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
1.93 s
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.000
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
8.76 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.
18.43 s
Page Load Progression
1.2 s 2.4 s
3.6 s
4.8 s
6.0 s
7.2 s
8.4 s
9.6 sDPage Weight BudgetAction2.4 MB transferred, 39 requestsFIX
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.
Source: web.dev
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
FJS Execution CostAction6973ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.uni-heidelberg.de/assets/index-C-OsSKiI.js | 3562ms | 2939ms | 12ms | 3rd |
| https://www.uni-heidelberg.de/en | 1797ms | 17ms | 43ms | 3rd |
| Unattributable | 1004ms | 9ms | 0ms | 3rd |
| https://www.uni-heidelberg.de/assets/tex-mml-chtml-3GpWM_o-.js | 610ms | 455ms | 153ms | 3rd |
DJS BundlesAction3 scripts, 444 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.uni-heidelberg.de/assets/index-C-OsSKiI.js | 822 KB | 289 KB (35%) | ✓ | 3rd |
| https://www.uni-heidelberg.de/assets/tex-mml-chtml-3GpWM_o-.js | 321 KB | 155 KB (48%) | ✓ | 3rd |
| https://cdn-eu.usefathom.com/script.js | 3 KB | — | ✓ | 3rd |
Consider code splitting or tree shaking to reduce unused code.
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.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
FPage Weight InventoryAction39 resources · 2.4 MB · 444 KB savings availableFIX
~443.8 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 39 resources | 2.4 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization21 images, 0 KB saveableREVIEW
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
A+Text CompressionAll text resources are compressedPASS
A+Font Loading3 fonts (44 KB)PASS
Web fonts
3
44 KB total
Render-blocking
0
of 3
Dominant font-display
swap
Most common across fonts
Font loading timeline
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 CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
Network Waterfall39 requests over 7260msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.uni-heidelberg.de www.uni-heidelberg.de | Other | 3562ms | 822 KB | 35% | €39/mo | Costly |
www.uni-heidelberg.de www.uni-heidelberg.de | Other | 1797ms | 44 KB | — | €20/mo | Costly |
Unattributable Unattributable | Other | 1004ms | 0 KB | — | €11/mo | Costly |
www.uni-heidelberg.de www.uni-heidelberg.de | Other | 610ms | 321 KB | 48% | €7/mo | Costly |
These scripts may cost more than they're worth
- www.uni-heidelberg.de adds 3562ms and costs ~€39/month
- www.uni-heidelberg.de adds 1797ms and costs ~€20/month
- Unattributable adds 1004ms and costs ~€11/month
- www.uni-heidelberg.de adds 610ms and costs ~€7/month
100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.
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.uni-heidelberg.de takes 3562ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.uni-heidelberg.de takes 1797ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Unattributable takes 1004ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.uni-heidelberg.de takes 610ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev