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.

5.80 s

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

5.84 s

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

506 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.

5.80 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.

6.48 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 4 REVIEW 2 FIX

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 (577.3 KiB of 577.5 KiB)

Third-party blocking time is low (0 ms)

100%

First-party Third-party

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

1452ms total JS execution

REVIEW

1452ms total JS execution

https://1c5c1ecf7303.eb59107c.us-west-1.token.awsw...: 921ms CPU time

Unattributable: 312ms CPU time

https://www.amazon.fr/: 120ms CPU time

https://images-na.ssl-images-amazon.com/images/G/0...: 100ms CPU time

Third-party scripts: 1452ms (100% of total)

Main Thread Breakdown

Script Evaluation 64% Other 21% Script Parsing & Compilation 10%

Script	Total	Scripting	Parse/Compile	Party
https://1c5c1ecf7303.eb59107c.us-west-1.token.awswaf.com/1c5c1ecf7303/0a0f47775f3e/ab24445d6425/challenge.js	921ms	695ms	147ms	3rd
Unattributable	312ms	124ms	0ms	3rd
https://www.amazon.fr/	120ms	52ms	4ms	3rd
https://images-na.ssl-images-amazon.com/images/G/01/AUIClients/ClientSideMetricsAUIJavascript-51171fbdd28e1a7a61e922e8f0272af8bc74d37b.secure.variant-desktop-session-snapshot-keypress.min._V2_.js	100ms	59ms	2ms	3rd

JS Bundles

Action

5 scripts, 280 KB unused

REVIEW

5 scripts, 280 KB unused

https://1c5c1ecf7303.eb59107c.us-west-1.token.awsw...: 280 KB unused (56%)

Consider code splitting or tree shaking to reduce unused code.

Total unused JavaScript: 280 KB

280 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://1c5c1ecf7303.eb59107c.us-west-1.token.awswaf.com/1c5c1ecf7303/0a0f47775f3e/ab24445d6425/challenge.js	501 KB	280 KB (56%)	✓	3rd
https://images-eu.ssl-images-amazon.com/images/G/01/csminstrumentation/csm-captcha-instrumentation.min.js	2 KB	—	✓	3rd
https://images-eu.ssl-images-amazon.com/images/G/01/csminstrumentation/rd-script-6d68177fa6061598e9509dc4b5bdd08d.js	2 KB	—	✓	3rd
https://images-na.ssl-images-amazon.com/images/G/01/csminstrumentation/ue-base-1c399ad9886cab69575e1e5ee15c61a1._V313498596_.js	3 KB	—	✓	3rd
https://images-na.ssl-images-amazon.com/images/G/01/AUIClients/ClientSideMetricsAUIJavascript-51171fbdd28e1a7a61e922e8f0272af8bc74d37b.secure.variant-desktop-session-snapshot-keypress.min._V2_.js	7 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

Page Weight Inventory

17 resources · 577 KB · 280 KB savings available

REVIEW

17 resources · 577 KB · 280 KB savings available

Within 1MB page-weight target

Got: 577 KB

~280 KB of savings available

16 third-party resources (100% of weight)

1 resources over 200KB

17 resources · 577.5 KiB · 16 third-party Within 1MB page-weight target

JavaScript 89% · 514.3 KiB

Image 6% · 35.1 KiB

CSS 4% · 21.1 KiB

Document 1% · 4.7 KiB

Other 0% · 2.2 KiB

~280.1 KiB of savings available

Remove unused JavaScript: 280.1 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

17 resources			577.5 KiB

Green Hosting

Action

Whether the site is served from green-energy infrastructure

REVIEW

Green Hosting

No green hosting detected

A+

Page Weight Budget

577 KB transferred, 17 requests

PASS

577 KB transferred, 17 requests

Page weighs 1.6 MB (577 KB transferred)

JavaScript is 514 KB — consider code splitting or lazy loading

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Got: 514 KB

17 HTTP requests

Estimated 0.12 g CO2 per page load

577 KB transferred

17 requests

0.12 g CO2 per page load

JavaScript 514.3 KiB 89%

CSS 21.1 KiB 4%

Other 18.0 KiB 3%

Images 17.3 KiB 3%

HTML 4.5 KiB 1%

Other 2.0 KiB 0%

Other 178 B 0%

0 2.4 MB 4.9 MB

Under budget

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

A+

Text Compression

All text resources are compressed

PASS

All text resources are compressed

All text resources are properly compressed.

Image Optimization

2 images, 0 KB saveable

PASS

2 images, 0 KB saveable

https://fls-eu.amazon.fr/1/oc-csi/1/OP/requestId=K... is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

2 images 17 KB

0 oversized -0 KB

2 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

A+

Font Loading

No web fonts (system fonts)

PASS

No web fonts (system fonts)

No web fonts loaded — system fonts are fastest

No web fonts loaded — system fonts are optimal.

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+

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

Network Waterfall

17 requests over 2499ms

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 1452ms · 510KB · €6/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
1c5c1ecf7303.eb59107c.us-west-1.token.awswaf.com 1c5c1ecf7303.eb59107c.us-west-1.token.awswaf.com	Other	921ms	501 KB	56%	€4/mo	Costly
Unattributable Unattributable	Other	312ms	0 KB	—	€1/mo	Costly
www.amazon.fr www.amazon.fr	Other	120ms	2 KB	—	€0/mo	Optional
images-na.ssl-images-amazon.com images-na.ssl-images-amazon.com	Other	100ms	7 KB	—	€0/mo	Optional

1c5c1ecf7303.eb59107c.us-west-1.token.awswaf.com

Other

Costly

Execution 921ms

Transfer 501 KB

Unused 56%

Monthly Cost €4/mo

Unattributable

Other

Costly

Execution 312ms

Transfer 0 KB

Monthly Cost €1/mo

www.amazon.fr

Other

Optional

Execution 120ms

Transfer 2 KB

Monthly Cost €0/mo

images-na.ssl-images-amazon.com

Other

Optional

Execution 100ms

Transfer 7 KB

Monthly Cost €0/mo

These scripts may cost more than they're worth

1c5c1ecf7303.eb59107c.us-west-1.token.awswaf.com adds 921ms and costs ~€4/month
Unattributable adds 312ms and costs ~€1/month

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

1c5c1ecf7303.eb59107c.us-west-1.token.awswaf.com takes 921ms 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

56% of 1c5c1ecf7303.eb59107c.us-west-1.token.awswaf.com's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

Unattributable takes 312ms 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.