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https://decathlon.com

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
70
GRADE
C
FIX
5
REVIEW
1
PASS
6
INFO
2

Performance-focused optimization plan with CWV assessment, top offenders, and time estimates

Mobile Desktop
81
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
95
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
81
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
85
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

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.

1.49 s

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

138 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.

4.39 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.

10.11 s

Page Load Progression

1.1 s
2.1 s
3.2 s
4.3 s
5.3 s
6.4 s
7.5 s
8.5 s
Checks
14
6 PASS 1 REVIEW 5 FIX
F
Page Weight Budget
Action
9.7 MB transferred, 414 requests
FIX
9.7 MB transferred, 414 requests
Critical::
Page weighs 17.6 MB (9.7 MB transferred)
Warning::
Images are 4.7 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 4.7 MB
Warning::
JavaScript is 2.9 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 2.9 MB
Info::
Fonts are 353 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 353 KB
Warning::
414 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 2.0 g CO2 per page load
9.7 MB / 2.4 MB budget
9.7 MB transferred
414 requests
2.0 g CO2 per page load
Images 4.7 MiB 49%
JavaScript 2.9 MiB 30%
Other 1.3 MiB 14%
Fonts 353.0 KiB 4%
Other 152.3 KiB 2%
CSS 113.4 KiB 1%
HTML 94.0 KiB 1%
Other 24.5 KiB 0%
Other 9.5 KiB 0%
Other 0 B 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

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

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

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Why this matters

High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.

Source: web.dev

D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (9.7 MiB of 9.7 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
JS Execution Cost
Action
4490ms total JS execution
FIX
4490ms total JS execution
Warning::
https://www.decathlon.com/: 1325ms CPU time
Warning::
Unattributable: 758ms CPU time
Warning::
https://cdn.dynamicyield.com/api/8773860/api_stati...: 402ms CPU time
Warning::
https://cdn.rebuyengine.com/onsite/js/rebuy.js?sho...: 351ms CPU time
Warning::
https://cdn.rebuyengine.com/onsite/js/global.js?bu...: 301ms CPU time
Warning::
Third-party scripts: 4490ms (100% of total)

Main Thread Breakdown

Script Evaluation 46% Style & Layout 21% Other 20% Script Parsing & Compilation 8%
ScriptTotalScriptingParse/CompileParty
https://www.decathlon.com/1325ms109ms12ms3rd
Unattributable758ms36ms0ms3rd
https://cdn.dynamicyield.com/api/8773860/api_static.js402ms111ms13ms3rd
https://cdn.rebuyengine.com/onsite/js/rebuy.js?shop=decathlon-usa.myshopify.com351ms191ms156ms3rd
https://cdn.rebuyengine.com/onsite/js/global.js?build=1775594982301ms244ms26ms3rd
https://scripts.clarity.ms/0.8.59/clarity.js216ms193ms3ms3rd
https://www.decathlon.com/cdn/wpm/b0e8c7c7aw41bd75a1p837d7fd4m8b145375m.js212ms122ms7ms3rd
https://static.klaviyo.com/onsite/js/build-preview/commit-98747c9b1816a2f78e748cdc073a286a0296d9f7/vendors~in_app_forms~signup_forms~reviews~atlas.0201e888d834a3782e3a.js?cb=2158ms86ms1ms3rd
https://www.googletagmanager.com/gtag/js?id=G-NQJCP882N4137ms113ms22ms3rd
https://assets.gorgias.chat/build/static/js/279.6ba6eb825556cdb4.js126ms105ms10ms3rd

Showing top 10 of 17 scripts

F
JS Bundles
Action
209 scripts, 812 KB unused
FIX
209 scripts, 812 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-NQJC...: 112 KB unused (65%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.rebuyengine.com/onsite/js/global.js?bu...: 111 KB unused (50%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.rebuyengine.com/onsite/js/vendors.js?i...: 87 KB unused (96%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-NQJC...: 66 KB unused (38%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=GT-MJW...: 60 KB unused (44%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 812 KB
812 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-NQJCP882N4&cx=c&gtm=4e6461174 KB112 KB (65%)✓3rd
https://cdn.rebuyengine.com/onsite/js/global.js?build=1775594982221 KB111 KB (50%)✓3rd
https://cdn.rebuyengine.com/onsite/js/vendors.js?id=ba81eedcc75447950e1491 KB87 KB (96%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-NQJCP882N4174 KB66 KB (38%)✓3rd
https://www.googletagmanager.com/gtag/js?id=GT-MJWCF3J136 KB60 KB (44%)✓3rd
https://assets.gorgias.chat/build/static/js/279.6ba6eb825556cdb4.js93 KB46 KB (49%)✓3rd
https://static.returngo.ai/master.returngo.ai/returngo.min.js?shop=decathlon-usa.myshopify.com50 KB44 KB (89%)✓3rd
https://static-tracking.klaviyo.com/onsite/js/build-preview/commit-98747c9b1816a2f78e748cdc073a286a0296d9f7/Render.f778b94f6021eec68929.js52 KB37 KB (72%)✓3rd
https://connect.facebook.net/en_US/fbevents.js95 KB32 KB (34%)✓3rd
https://connect.facebook.net/en_US/fbevents.js95 KB32 KB (34%)✓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

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

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

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

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

D
HTTP Caching
Action
no-store (uncacheable)
FIX
no-store (uncacheable)
Info::
Cache-Control: no-store prevents all caching
Intentional for dynamic content, but increases server load for every page view.
Got: private, max-age=0, no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

private, max-age=0, no-store, no-cache, must-revalidate, post-check=0, pre-check=0

DirectiveValueMeaning
private—Only browser cache, not CDN/proxy
max-age0Cache for 0 seconds
no-store—Never cache this response
no-cache—Cache but always revalidate first
must-revalidate—Must recheck with server after expiry
post-check0
pre-check0
C
Image Optimization
Action
44 images, 0 KB saveable
REVIEW
44 images, 0 KB saveable
Warning::
https://cdn.shopify.com/s/files/1/1330/6287/files/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.shopify.com/s/files/1/1330/6287/files/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.shopify.com/s/files/1/1752/4727/files/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.shopify.com/s/files/1/1752/4727/files/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.shopify.com/s/files/1/1330/6287/files/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
44 images 4.7 MB
0 oversized -0 KB
14 legacy format
5 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

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

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

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

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+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Font Loading
9 fonts (353 KB)
PASS
9 fonts (353 KB)
Info::
9 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

9

353 KB total

Render-blocking

0

of 9

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s FCP 1.2 s LCP 1.5 shttps://www.decathlon.com/cdn/shop/t/334/assets/Decathlon-Brand-SemiBold.woff2?v=4101535601310826581750076865Decathlon-Brand-SemiBol... https://www.decathlon.com/cdn/shop/t/334/assets/Decathlon-Brand-SemiBold.woff2?v=4101535601310826581750076865 — 0 B — 0 ms — font-display: swaphttps://www.decathlon.com/cdn/shop/t/334/assets/Decathlon-Display-SemiBold.woff2?v=100345316253960588891750076865Decathlon-Display-SemiB... https://www.decathlon.com/cdn/shop/t/334/assets/Decathlon-Display-SemiBold.woff2?v=100345316253960588891750076865 — 0 B — 0 ms — font-display: swaphttps://www.decathlon.com/cdn/shop/t/334/assets/Decathlon-Text-Medium.woff2?v=52324173899180483681750076865Decathlon-Text-Medium.w... https://www.decathlon.com/cdn/shop/t/334/assets/Decathlon-Text-Medium.woff2?v=52324173899180483681750076865 — 0 B — 0 ms — font-display: swaphttps://www.decathlon.com/cdn/shop/t/334/assets/Decathlon-Text-SemiBold.woff2?v=2220433650020876521750076866Decathlon-Text-SemiBold... https://www.decathlon.com/cdn/shop/t/334/assets/Decathlon-Text-SemiBold.woff2?v=2220433650020876521750076866 — 0 B — 0 ms — font-display: swaphttps://www.decathlon.com/cdn/fonts/assistant/assistant_n4.9120912a469cad1cc292572851508ca49d12e768.woff2assistant_n4.9120912a46... https://www.decathlon.com/cdn/fonts/assistant/assistant_n4.9120912a469cad1cc292572851508ca49d12e768.woff2 — 12.7 KiB — 0 ms — font-display: swaphttps://cdn.rebuyengine.com/onsite/webfonts/fa-light-300.woff2fa-light-300.woff2 https://cdn.rebuyengine.com/onsite/webfonts/fa-light-300.woff2 — 185.8 KiB — 0 ms — font-display: swaphttps://cdn.shopify.com/s/files/1/1330/6287/files/Decathlon-Display-Bold.ttf?v=1759350281Decathlon-Display-Bold.ttf https://cdn.shopify.com/s/files/1/1330/6287/files/Decathlon-Display-Bold.ttf?v=1759350281 — 51.5 KiB — 0 ms — font-display: swaphttps://cdn.shopify.com/s/files/1/1330/6287/files/Decathlon-Display-SemiBold.ttf?v=1759350281Decathlon-Display-SemiB... https://cdn.shopify.com/s/files/1/1330/6287/files/Decathlon-Display-SemiBold.ttf?v=1759350281 — 51.5 KiB — 0 ms — font-display: swaphttps://cdn.shopify.com/s/files/1/1330/6287/files/Decathlon-Display-Medium.ttf?v=1759350281Decathlon-Display-Mediu... https://cdn.shopify.com/s/files/1/1330/6287/files/Decathlon-Display-Medium.ttf?v=1759350281 — 51.5 KiB — 0 ms — font-display: swap
Decathlon-Brand-SemiBol... woff2 swap
Size 0 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Decathlon-Display-SemiB... woff2 swap
Size 0 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Decathlon-Text-Medium.w... woff2 swap
Size 0 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Decathlon-Text-SemiBold... woff2 swap
Size 0 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
assistant_n4.9120912a46... woff2 swap
Size 13 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
fa-light-300.woff2 woff2 swap
Size 186 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
Decathlon-Display-Bold.ttf ttf swap
Size 52 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
Decathlon-Display-SemiB... ttf swap
Size 52 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
Decathlon-Display-Mediu... ttf swap
Size 51 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
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)

Fixing the unchecked items could save ~139 KB and ~278 ms

A+
Resource Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Cloudflare

Network Waterfall
414 requests over 0ms
INFO

Performance analysis not available for this result.

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 4490ms · 1117KB · €24/mo
www.decathlon.com
Other
Costly
Execution 1325ms
Transfer 80 KB
Monthly Cost €7/mo
Unattributable
Other
Costly
Execution 758ms
Transfer 0 KB
Monthly Cost €4/mo
cdn.dynamicyield.com
Other
Costly
Execution 402ms
Transfer 112 KB
Unused 67%
Monthly Cost €2/mo
cdn.rebuyengine.com
Other
Costly
Execution 351ms
Transfer 20 KB
Monthly Cost €2/mo
cdn.rebuyengine.com
Other
Costly
Execution 301ms
Transfer 221 KB
Unused 50%
Monthly Cost €2/mo
Microsoft Clarity
Session Replay
Costly
Execution 216ms
Transfer 26 KB
Monthly Cost €1/mo
www.decathlon.com
Other
Costly
Execution 212ms
Transfer 61 KB
Unused 38%
Monthly Cost €1/mo
static.klaviyo.com
Other
Optional
Execution 158ms
Transfer 10 KB
Monthly Cost €1/mo
Google Tag Manager
Tag Manager
Optional
Execution 137ms
Transfer 174 KB
Unused 38%
Monthly Cost €1/mo
assets.gorgias.chat
Other
Optional
Execution 126ms
Transfer 93 KB
Unused 49%
Monthly Cost €1/mo
st.dynamicyield.com
Other
Optional
Execution 96ms
Transfer 5 KB
Monthly Cost €1/mo
Google Tag Manager
Tag Manager
Optional
Execution 87ms
Transfer 136 KB
Unused 44%
Monthly Cost €0/mo
static.klaviyo.com
Other
Optional
Execution 86ms
Transfer 8 KB
Monthly Cost €0/mo
www.decathlon.com
Other
Optional
Execution 70ms
Transfer 28 KB
Monthly Cost €0/mo
Facebook Pixel
Advertising
Optional
Execution 60ms
Transfer 95 KB
Unused 34%
Monthly Cost €0/mo
cdn.rebuyengine.com
Other
Optional
Execution 54ms
Transfer 44 KB
Unused 57%
Monthly Cost €0/mo
static-tracking.klaviyo.com
Other
Optional
Execution 53ms
Transfer 5 KB
Monthly Cost €0/mo

These scripts may cost more than they're worth

  • www.decathlon.com adds 1325ms and costs ~€7/month
  • Unattributable adds 758ms and costs ~€4/month
  • cdn.dynamicyield.com adds 402ms and costs ~€2/month
  • cdn.rebuyengine.com adds 351ms and costs ~€2/month
  • cdn.rebuyengine.com adds 301ms and costs ~€2/month
  • Microsoft Clarity adds 216ms and costs ~€1/month
  • www.decathlon.com adds 212ms 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

www.decathlon.com takes 1325ms 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

Unattributable takes 758ms 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

cdn.dynamicyield.com takes 402ms 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

67% of cdn.dynamicyield.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

cdn.rebuyengine.com takes 351ms 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

cdn.rebuyengine.com takes 301ms 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

50% of cdn.rebuyengine.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

Microsoft Clarity takes 216ms 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

www.decathlon.com takes 212ms 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

57% of cdn.rebuyengine.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

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.

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