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https://www.shein.com

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
71
GRADE
C
FIX
5
REVIEW
0
PASS
7
INFO
2

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

Mobile Desktop
61
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
92
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
77
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
77
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.

946 ms

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

3.29 s

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

278 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.

3.73 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.

3.30 s

Page Load Progression

5.3 s
10.5 s
15.8 s
21.0 s
26.3 s
31.6 s
36.8 s
42.1 s
Checks
14
7 PASS 5 FIX
F
Page Weight Budget
Action
4.2 MB transferred, 447 requests
FIX
4.2 MB transferred, 447 requests
Critical::
Page weighs 9.8 MB (4.2 MB transferred)
Warning::
JavaScript is 690 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 690 KB
Warning::
447 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 0.88 g CO2 per page load
4.2 MB / 2.4 MB budget
4.2 MB transferred
447 requests
0.88 g CO2 per page load
Other 2.1 MiB 51%
Images 892.6 KiB 21%
JavaScript 689.7 KiB 16%
HTML 196.4 KiB 5%
Other 164.5 KiB 4%
Other 100.1 KiB 2%
Fonts 84.1 KiB 2%
CSS 1.8 KiB 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over 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

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 (4.2 MiB of 4.2 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
JS Execution Cost
Action
3587ms total JS execution
FIX
3587ms total JS execution
Warning::
https://sc.ltwebstatic.com/she_dist/assets/swiper-...: 1605ms CPU time
Warning::
Unattributable: 426ms CPU time
Warning::
https://es.shein.com/?cdn_rsite=cf&ref=www&rep=dir...: 298ms CPU time
Warning::
https://sc.ltwebstatic.com/she_dist/assets/ccc-hom...: 279ms CPU time
Warning::
https://armor.ltwebstatic.com/she_dist/armor-libs/...: 262ms CPU time
Warning::
Third-party scripts: 3587ms (100% of total)

Main Thread Breakdown

Script Evaluation 54% Other 33% Style & Layout 5% Script Parsing & Compilation 3%
ScriptTotalScriptingParse/CompileParty
https://sc.ltwebstatic.com/she_dist/assets/swiper-c0c12f20c8993279.js1605ms688ms2ms3rd
Unattributable426ms8ms0ms3rd
https://es.shein.com/?cdn_rsite=cf&ref=www&rep=dir&ret=es298ms84ms18ms3rd
https://sc.ltwebstatic.com/she_dist/assets/ccc-home-34f82514a91254ee.js279ms256ms1ms3rd
https://armor.ltwebstatic.com/she_dist/armor-libs/infp/infp.3.11.1.min.js262ms212ms7ms3rd
https://sc.ltwebstatic.com/she_dist/assets/common-95446e340c4d2a59.js245ms211ms0ms3rd
https://sc.ltwebstatic.com/she_dist/assets/51769-e709c6d373442394.js111ms101ms2ms3rd
https://sc.ltwebstatic.com/she_dist/assets/64556-9eba928d99e7ca4f.js90ms75ms1ms3rd
https://es.shein.com/cdn-cgi/challenge-platform/scripts/jsd/main.js73ms64ms1ms3rd
https://sc.ltwebstatic.com/she_dist/assets/bff-ccc-one-third.c0075c8ee2809c65.js71ms57ms4ms3rd

Showing top 10 of 12 scripts

F
JS Bundles
Action
206 scripts, 4.8 MB unused
FIX
206 scripts, 4.8 MB unused
Warning::
https://sc.ltwebstatic.com/she_dist/assets/lib-sui...: 269 KB unused (58%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://sc.ltwebstatic.com/she_dist/assets/lib-sui...: 269 KB unused (58%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://sc.ltwebstatic.com/she_dist/assets/lib-sui...: 269 KB unused (58%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://sc.ltwebstatic.com/she_dist/assets/lib-sui...: 269 KB unused (58%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://sc.ltwebstatic.com/she_dist/assets/24609-f...: 212 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 4.8 MB
4949 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://sc.ltwebstatic.com/she_dist/assets/lib-sui-814096f7d7bbe058.js0 KB269 KB (58%)✓3rd
https://sc.ltwebstatic.com/she_dist/assets/lib-sui-814096f7d7bbe058.js0 KB269 KB (58%)✓3rd
https://sc.ltwebstatic.com/she_dist/assets/lib-sui-814096f7d7bbe058.js94 KB269 KB (58%)✓3rd
https://sc.ltwebstatic.com/she_dist/assets/lib-sui-814096f7d7bbe058.js0 KB269 KB (58%)✓3rd
https://sc.ltwebstatic.com/she_dist/assets/24609-f35da72716c9908d.js0 KB212 KB (42%)✓3rd
https://sc.ltwebstatic.com/she_dist/assets/24609-f35da72716c9908d.js0 KB212 KB (42%)✓3rd
https://sc.ltwebstatic.com/she_dist/assets/24609-f35da72716c9908d.js0 KB212 KB (42%)✓3rd
https://sc.ltwebstatic.com/she_dist/assets/24609-f35da72716c9908d.js81 KB212 KB (42%)✓3rd
https://sc.ltwebstatic.com/she_dist/assets/912-c12224ed74211be1.js0 KB186 KB (32%)✓3rd
https://sc.ltwebstatic.com/she_dist/assets/912-c12224ed74211be1.js136 KB186 KB (32%)✓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

F
HTTP Caching
Action
No cache headers
FIX
No cache headers
Warning::
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.

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
Image Optimization
65 images, 0 KB saveable
PASS
65 images, 0 KB saveable
Warning::
https://shein.ltwebstatic.com/svgicons/2026/03/18/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
65 images 893 KB
0 oversized -0 KB
1 legacy format
2 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

Performance issues directly impact user engagement and conversion rates.

A+
Font Loading
3 fonts (84 KB)
PASS
3 fonts (84 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

84 KB total

Render-blocking

0

of 3

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 1.0 s 2.0 s 3.0 s FCP 946 ms LCP 3.3 shttps://sc.ltwebstatic.com/she_dist/font/muli-v16-latin-700.woff2muli-v16-latin-700.woff2 https://sc.ltwebstatic.com/she_dist/font/muli-v16-latin-700.woff2 — 17.3 KiB — 0 ms — font-display: swaphttps://sc.ltwebstatic.com/she_dist/font/muli-v13-latin-regular.woff2muli-v13-latin-regular.... https://sc.ltwebstatic.com/she_dist/font/muli-v13-latin-regular.woff2 — 17.3 KiB — 0 ms — font-display: swaphttps://sc.ltwebstatic.com/she_dist/font/Jost-VariableFont_wght.woff2Jost-VariableFont_wght.... https://sc.ltwebstatic.com/she_dist/font/Jost-VariableFont_wght.woff2 — 49.5 KiB — 0 ms — font-display: swap
muli-v16-latin-700.woff2 woff2 swap
Size 17 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
muli-v13-latin-regular.... woff2 swap
Size 17 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Jost-VariableFont_wght.... woff2 swap
Size 50 KB
Load time 0 ms
Start 0 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+
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
447 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 3587ms · 353KB · S$62/mo
sc.ltwebstatic.com
Other
Costly
Execution 1605ms
Transfer 0 KB
Unused 48%
Monthly Cost S$28/mo
Unattributable
Other
Costly
Execution 426ms
Transfer 0 KB
Monthly Cost S$7/mo
es.shein.com
Other
Costly
Execution 298ms
Transfer 196 KB
Monthly Cost S$5/mo
sc.ltwebstatic.com
Other
Costly
Execution 279ms
Transfer 0 KB
Monthly Cost S$5/mo
armor.ltwebstatic.com
Other
Costly
Execution 262ms
Transfer 111 KB
Unused 23%
Monthly Cost S$5/mo
sc.ltwebstatic.com
Other
Costly
Execution 245ms
Transfer 0 KB
Monthly Cost S$4/mo
sc.ltwebstatic.com
Other
Optional
Execution 111ms
Transfer 0 KB
Unused 47%
Monthly Cost S$2/mo
sc.ltwebstatic.com
Other
Optional
Execution 90ms
Transfer 0 KB
Monthly Cost S$2/mo
es.shein.com
Other
Optional
Execution 73ms
Transfer 0 KB
Monthly Cost S$1/mo
sc.ltwebstatic.com
Other
Optional
Execution 71ms
Transfer 45 KB
Monthly Cost S$1/mo
sc.ltwebstatic.com
Other
Optional
Execution 65ms
Transfer 0 KB
Monthly Cost S$1/mo
armor.ltwebstatic.com
Other
Optional
Execution 64ms
Transfer 0 KB
Unused 28%
Monthly Cost S$1/mo

These scripts may cost more than they're worth

  • sc.ltwebstatic.com adds 1605ms and costs ~S$28/month
  • Unattributable adds 426ms and costs ~S$7/month
  • es.shein.com adds 298ms and costs ~S$5/month
  • sc.ltwebstatic.com adds 279ms and costs ~S$5/month
  • armor.ltwebstatic.com adds 262ms and costs ~S$5/month
  • sc.ltwebstatic.com adds 245ms and costs ~S$4/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

sc.ltwebstatic.com takes 1605ms 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 426ms 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

es.shein.com takes 298ms 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

sc.ltwebstatic.com takes 279ms 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

armor.ltwebstatic.com takes 262ms 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

sc.ltwebstatic.com takes 245ms 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.

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