Performance

· 23 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

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.

1.19 s

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

1.59 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.

0.001

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

1.19 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.

1.59 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

9 PASS 6 REVIEW 4 FIX

Page Weight Budget

Action

2.6 MB transferred, 19 requests

FIX

2.6 MB transferred, 19 requests

Page weighs 2.6 MB (2.6 MB transferred)

Images are 2.5 MB — compress or use modern formats

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

Got: 2.5 MB

19 HTTP requests

Estimated 0.55 g CO2 per page load

2.6 MB transferred

19 requests

0.55 g CO2 per page load

Images 2.5 MiB 97%

Fonts 73.1 KiB 3%

HTML 5.1 KiB 0%

Other 1.5 KiB 0%

CSS 1.3 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

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 (2.6 MiB of 2.6 MiB)

Third-party blocking time is low (0 ms)

100%

First-party Third-party

Page Weight Inventory

Action

19 resources · 2.6 MB · 0 KB savings available

FIX

19 resources · 2.6 MB · 0 KB savings available

Page weight 2.6 MB exceeds 1 MB target by 1.6 MB

Got: 2.6 MB Expected: ≤ 1 MB

18 third-party resources (100% of weight)

3 resources over 200KB

19 resources · 2.6 MiB · 18 third-party 1.6 MiB over 1MB target

Image 97% · 2.5 MiB

Font 3% · 73.1 KiB

Document 0% · 6.5 KiB

CSS 0% · 1.3 KiB

Other 0% · 139 B

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

19 resources			2.6 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

13 images, 0 KB saveable

REVIEW

13 images, 0 KB saveable

https://images.unsplash.com/photo-1556909172-54557... is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

13 images 2.5 MB

0 oversized -0 KB

13 legacy format

1 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

HTTP/3 (QUIC)

HTTP/3 not advertised

REVIEW

HTTP/3 not advertised

HTTP/3 (QUIC) is not advertised

HTTP/3 isn't advertised via Alt-Svc and the worker didn't negotiate h3. HTTP/3 reduces handshake latency (1-RTT instead of 2-3 RTTs) and is more resilient on lossy connections. Most modern CDNs (Cloudflare, Fastly, AWS CloudFront, Google Cloud CDN) support HTTP/3 with a single config switch -- consider enabling for mobile-heavy workloads.

Document Compression

Action

Document response served uncompressed

REVIEW

Document response served uncompressed

Main HTML response has no Content-Encoding (uncompressed)

The main HTML document is served without compression. The Text Compression section above lists the broader picture; for the main response specifically, even gzip would shave ~70-80% off most text payloads.

Main HTML Cache-Control

No Cache-Control header on main HTML response

REVIEW

No Cache-Control header on main HTML response

Main HTML response has no Cache-Control header

Without an explicit Cache-Control, browsers fall back to heuristic caching (~10% of Last-Modified age). Set `Cache-Control: no-cache` or `max-age=300` for HTML to control freshness explicitly -- prevents stale auth state and SPA shell drift.

Server-Timing Observability

No Server-Timing header found

REVIEW

No Server-Timing header found

Server-Timing exposes backend timing breakdowns to browser DevTools (e.g., `db: 45ms; render: 120ms; cache: 2ms`). Useful for diagnosing slow pages without backend log access. Most modern frameworks (Next.js, Cloudflare Workers, Fastly) emit it automatically; absence on a managed platform usually means telemetry headers are stripped at the edge.

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

148ms total JS execution

PASS

148ms total JS execution

https://cleanspace.ch/: 148ms CPU time

Third-party scripts: 148ms (100% of total)

Main Thread Breakdown

Other 76% Style & Layout 17%

Script	Total	Scripting	Parse/Compile	Party
https://cleanspace.ch/	148ms	3ms	0ms	3rd

A+

Font Loading

2 fonts (73 KB)

PASS

2 fonts (73 KB)

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

Web fonts

73 KB total

Render-blocking

of 2

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

co3bmX5slCNuHLi8bLeY9MK... woff2 swap

Size 37 KB

Load time 44 ms

Start 239 ms

Risk FOUT — text flashes from fallback to web font

rP2Yp2ywxg089UriI5-g4vl... woff2 swap

Size 36 KB

Load time 41 ms

Start 240 ms

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

No JavaScript

PASS

No JavaScript

No JavaScript bundles

No JavaScript files loaded.

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+

LCP Image Preload

LCP preload audit not available

PASS

LCP preload audit not available

LCP image preload audit not available for this scan

A+

Server Response Intelligence

1 server-response signal(s) detected

PASS

1 server-response signal(s) detected

No `ETag` or `Last-Modified` -- conditional GET not supported

Without either header, browsers can't issue conditional GETs and refresh always re-downloads the full response body even when nothing changed. Add `ETag: "<hash>"` (or `Last-Modified: <date>`) on cacheable responses; the server returns 304 Not Modified when the client's cached copy is still valid, saving bandwidth.

Asset Compression

No text asset hosts to measure

INFO

No text asset hosts to measure

No third-party or subdomain host served enough text assets to measure

Asset compression is measured per host, from one HEAD request against a sampled resource. Pages that serve all their JS and CSS from the document's own origin are covered by the document compression check instead.

Network Waterfall

19 requests over 676ms

INFO

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 148ms · 5KB · CHF2/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
cleanspace.ch cleanspace.ch	Other	148ms	5 KB	—	CHF2/mo	Optional

cleanspace.ch

Other

Optional

Execution 148ms

Transfer 5 KB

Monthly Cost CHF2/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

How third-party costs are calculated

Image Optimization

14 images, 2613 KB total, 1515 KB wasted

INFO

Image Optimization Audit

Total Images

Total Size

2613 KB

Oversized

Wasted

1515 KB

14 missing dimensions 8 missing lazy loading

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