Performance

· 26 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

100

SEO

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

1.37 s

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

2.57 s

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

56 ms

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.

1.59 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.

2.89 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

17 PASS 5 REVIEW 1 FIX

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.

JS Execution Cost

Action

1603ms total JS execution

REVIEW

1603ms total JS execution

https://svennouwen.nl/: 761ms CPU time

https://svennouwen.nl/wp-includes/js/jquery/jquery...: 376ms CPU time

Unattributable: 358ms CPU time

https://svennouwen.nl/wp-content/themes/jupiterx/l...: 109ms CPU time

Main Thread Breakdown

Script Evaluation 31% Style & Layout 29% Other 23% Parse HTML & CSS 7% Script Parsing & Compilation 6%

Script	Total	Scripting	Parse/Compile	Party
https://svennouwen.nl/	761ms	62ms	21ms	1st
https://svennouwen.nl/wp-includes/js/jquery/jquery.min.js?ver=3.7.1	376ms	311ms	17ms	1st
Unattributable	358ms	12ms	0ms	1st
https://svennouwen.nl/wp-content/themes/jupiterx/lib/assets/dist/js/frontend.min.js?ver=4.61.0	109ms	39ms	25ms	1st

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

Document response uses gzip; brotli would be ~20% smaller

REVIEW

Document response uses gzip; brotli would be ~20% smaller

Main HTML response uses gzip (brotli would be ~20% smaller)

All current browsers support brotli. Most CDNs (Cloudflare, Fastly, AWS CloudFront, Vercel, Netlify) can switch from gzip to brotli with a single config flag. Origin servers (nginx, Apache) need a brotli module compiled in -- nginx-brotli or Apache mod_brotli.

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.

A+

Page Weight Budget

389 KB transferred, 25 requests

PASS

389 KB transferred, 25 requests

Page weighs 1021 KB (389 KB transferred)

25 HTTP requests

Estimated 0.08 g CO2 per page load

389 KB transferred

25 requests

0.08 g CO2 per page load

JavaScript 143.1 KiB 37%

Images 137.9 KiB 35%

Fonts 48.0 KiB 12%

CSS 32.0 KiB 8%

HTML 26.2 KiB 7%

Other 1.2 KiB 0%

Other 170 B 0%

0 2.4 MB 4.9 MB

Under budget

A+

Third-Party Impact

No third-party resources

PASS

No third-party resources

No third-party resources detected

No third-party resources detected — all resources are first-party.

A+

Text Compression

All text resources are compressed

PASS

All text resources are compressed

All text resources are properly compressed.

Image Optimization

3 images, 0 KB saveable

PASS

3 images, 0 KB saveable

All images are well-optimized

3 images 138 KB

0 oversized -0 KB

3 legacy format

0 missing dimensions CLS risk

A+

Font Loading

4 fonts (48 KB)

PASS

4 fonts (48 KB)

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

Web fonts

48 KB total

Render-blocking

of 4

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

plus-jakarta-sans-latin... woff2 swap

Size 12 KB

Load time 42 ms

Start 313 ms

Risk FOUT — text flashes from fallback to web font

plus-jakarta-sans-latin... woff2 swap

Size 12 KB

Load time 42 ms

Start 315 ms

Risk FOUT — text flashes from fallback to web font

plus-jakarta-sans-latin... woff2 swap

Size 12 KB

Load time 13 ms

Start 529 ms

Risk FOUT — text flashes from fallback to web font

plus-jakarta-sans-latin... woff2 swap

Size 12 KB

Load time 29 ms

Start 529 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

12 scripts, 32 KB unused

PASS

12 scripts, 32 KB unused

https://svennouwen.nl/wp-content/themes/jupiterx/l...: 32 KB unused (84%)

Consider code splitting or tree shaking to reduce unused code.

Total unused JavaScript: 32 KB

32 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://svennouwen.nl/wp-content/themes/jupiterx/lib/assets/dist/js/frontend.min.js?ver=4.61.0	39 KB	32 KB (84%)	✓	1st
https://svennouwen.nl/wp-includes/js/jquery/jquery.min.js?ver=3.7.1	30 KB	—	✓	1st
https://svennouwen.nl/wp-content/themes/jupiterx/lib/assets/dist/js/utils.min.js?ver=4.61.0	0 KB	—	✓	1st
https://svennouwen.nl/wp-includes/js/underscore.min.js?ver=1.13.8	7 KB	—	✓	1st
https://svennouwen.nl/wp-content/plugins/elementor/assets/js/webpack.runtime.min.js?ver=4.3.2	0 KB	—	✓	1st
https://svennouwen.nl/wp-content/plugins/elementor/assets/js/frontend-modules.min.js?ver=4.3.2	16 KB	—	✓	1st
https://svennouwen.nl/wp-includes/js/jquery/ui/core.min.js?ver=1.14.2	7 KB	—	✓	1st
https://svennouwen.nl/wp-content/plugins/elementor/assets/js/frontend.min.js?ver=4.3.2	19 KB	—	✓	1st
https://svennouwen.nl/wp-includes/js/wp-util.min.js?ver=7.1.2	1 KB	—	✓	1st
https://svennouwen.nl/wp-content/plugins/elementor/assets/js/chunks/background-slideshow.min.js?ver=4.3.2	8 KB	—	✓	1st

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

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

2 hints, 0 missing preconnects

PASS

2 hints, 0 missing preconnects

Page uses 2 resource hint(s)

Current Resource Hints

preconnect

—

preload

dns-prefetch

—

prefetch

—

2 resource hints configured

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

2 server-response signal(s) detected

PASS

2 server-response signal(s) detected

`Vary` header declared: Accept-Encoding

The page declares a `Vary` header, telling downstream caches which request headers the response varies on. Critical for content-negotiated responses (compression, language, cookies, device class).

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.

A+

Page Weight Inventory

25 resources · 389 KB · 32 KB savings available

PASS

25 resources · 389 KB · 32 KB savings available

Within 1MB page-weight target

Got: 389 KB

25 resources · 388.6 KiB · 0 third-party Within 1MB page-weight target

JavaScript 37% · 143.1 KiB

Image 36% · 139.0 KiB

Font 12% · 48.0 KiB

CSS 8% · 32.0 KiB

Document 7% · 26.2 KiB

Other 0% · 170 B

~32.4 KiB of savings available

Remove unused JavaScript: 32.4 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

25 resources			388.6 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

A+

JavaScript Blocking

No render-blocking JS or document.write usage detected

PASS

No render-blocking JS or document.write usage detected

No JavaScript blocking issues detected

A+

CSS Performance Depth

No CSS performance depth issues detected

PASS

No CSS performance depth issues detected

A+

Green Hosting

Whether the site is served from green-energy infrastructure

PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Combell

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

25 requests over 724ms

INFO

HTML JavaScript CSS Images Fonts XHR/Fetch Other

Image Optimization

5 images, 54 KB total, 36 KB wasted

INFO

Image Optimization Audit

Total Images

Total Size

54 KB

Oversized

Wasted

36 KB

3 missing lazy loading

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