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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
73
GRADE
C
FIX
4
REVIEW
3
PASS
5
INFO
2

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

Mobile Desktop
54
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
100
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.
92
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.

1.29 s

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

3.20 s

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

495 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.

2.03 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.

4.60 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
14
5 PASS 3 REVIEW 4 FIX
F
Page Weight Budget
Action
3.4 MB transferred, 108 requests
FIX
3.4 MB transferred, 108 requests
Warning::
Page weighs 10.8 MB (3.4 MB transferred)
Warning::
JavaScript is 2.5 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 2.5 MB
Info::
Fonts are 518 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 518 KB
Warning::
108 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 0.71 g CO2 per page load
3.4 MB / 2.4 MB budget
3.4 MB transferred
108 requests
0.71 g CO2 per page load
JavaScript 2.5 MiB 74%
Fonts 517.8 KiB 15%
Other 122.2 KiB 4%
Images 89.4 KiB 3%
HTML 87.9 KiB 3%
CSS 57.7 KiB 2%
Other 24.2 KiB 1%
Other 4.4 KiB 0%
Other 388 B 0%
Other 123 B 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

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
61% third-party, 0 ms blocking
FIX
61% third-party, 0 ms blocking
Warning::
Third-party code accounts for 61% of page weight (2.1 MiB of 3.4 MiB)
Info::
Third-party blocking time is low (0 ms)
39%
61%
First-party Third-party
F
JS Bundles
Action
38 scripts, 1.3 MB unused
FIX
38 scripts, 1.3 MB unused
Warning::
https://www.zara.com/stdstatic-recoms/recom-chat-0...: 740 KB unused (74%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://static.zara.net/stdstatic/8.10.0/js/v2/ven...: 149 KB unused (62%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-NOTF...: 71 KB unused (52%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=AW-983...: 66 KB unused (46%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.cookielaw.org/scripttemplates/202510.2...: 64 KB unused (52%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 1.3 MB
1322 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.zara.com/stdstatic-recoms/recom-chat-0.22.1/za/web/recom-chat.js1008 KB740 KB (74%)✓1st
https://static.zara.net/stdstatic/8.10.0/js/v2/vendor-v2.js242 KB149 KB (62%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-NOTFORGA4TRACKING&cx=c&gtm=4e6460136 KB71 KB (52%)✓3rd
https://www.googletagmanager.com/gtag/js?id=AW-983274422&cx=c&gtm=4e6460143 KB66 KB (46%)✓3rd
https://cdn.cookielaw.org/scripttemplates/202510.2.0/otBannerSdk.js124 KB64 KB (52%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-NK4BSSL169 KB63 KB (37%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-5CVGN7D&l=analyticsDataLayer141 KB61 KB (43%)✓3rd
https://bdyoomvaq5bp.eu.wpi.jscrambler.com/8j3lcd6j46o2/1588655105.js90 KB38 KB (43%)✓3rd
https://static.zara.net/stdstatic/8.10.0/js/v2/app-std-v2.js104 KB36 KB (35%)✓3rd
https://www.zara.com/8dp0grBL/6T3SaO1/F9Otr_x/o4/EEaVpwiaL3iOaOcE/CyJwZQ/Rg4XZBBG/ElgB168 KB35 KB (21%)✓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

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.

B
Image Optimization
12 images, 0 KB saveable
REVIEW
12 images, 0 KB saveable
Info::
All images are well-optimized
12 images 89 KB
0 oversized -0 KB
10 legacy format
0 missing dimensions CLS risk
C
JS Execution Cost
Action
1966ms total JS execution
REVIEW
1966ms total JS execution
Warning::
https://www.zara.com/stdstatic-recoms/recom-chat-0...: 445ms CPU time
Warning::
Unattributable: 319ms CPU time
Warning::
https://www.zara.com/8dp0grBL/6T3SaO1/F9Otr_x/o4/E...: 289ms CPU time
Info::
https://www.zara.com/: 232ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-NK4...: 201ms CPU time
Warning::
Third-party scripts: 1000ms (51% of total)

Main Thread Breakdown

Script Evaluation 63% Other 14% Script Parsing & Compilation 14% Style & Layout 4%
ScriptTotalScriptingParse/CompileParty
https://www.zara.com/stdstatic-recoms/recom-chat-0.22.1/za/web/recom-chat.js445ms324ms117ms1st
Unattributable319ms49ms0ms3rd
https://www.zara.com/8dp0grBL/6T3SaO1/F9Otr_x/o4/EEaVpwiaL3iOaOcE/CyJwZQ/Rg4XZBBG/ElgB289ms237ms17ms1st
https://www.zara.com/232ms75ms31ms1st
https://www.googletagmanager.com/gtm.js?id=GTM-NK4BSSL201ms172ms16ms3rd
https://bdyoomvaq5bp.eu.wpi.jscrambler.com/8j3lcd6j46o2/1588655105.js96ms77ms12ms3rd
https://static.zara.net/stdstatic/8.10.0/js/v2/vendor-v2.js94ms60ms26ms3rd
https://static.zara.net/stdstatic/8.10.0/js/v2/app-std-v2.js90ms77ms13ms3rd
https://cdn.cookielaw.org/scripttemplates/202510.2.0/otBannerSdk.js83ms55ms15ms3rd
https://www.googletagmanager.com/gtag/js?id=AW-983274422&cx=c&gtm=4e646064ms49ms14ms3rd

Showing top 10 of 11 scripts

C
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
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Font Loading
11 fonts (518 KB)
PASS
11 fonts (518 KB)
Info::
11 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

11

518 KB total

Render-blocking

0

of 11

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 1.3 s LCP 3.2 shttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_normal_700-FFDNP4JM.2bd77b8f.woff2helveticanowtext_normal... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_normal_700-FFDNP4JM.2bd77b8f.woff2 — 35.1 KiB — 0 ms — font-display: swaphttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_normal_500-EYZFBSEJ.7903c548.woff2helveticanowtext_normal... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_normal_500-EYZFBSEJ.7903c548.woff2 — 36.4 KiB — 0 ms — font-display: swaphttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_normal_400-J7L37R2S.ff8d68de.woff2helveticanowtext_normal... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_normal_400-J7L37R2S.ff8d68de.woff2 — 34.6 KiB — 0 ms — font-display: swaphttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_normal_300-FXIQ6PXP.ac45821f.woff2helveticanowtext_normal... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_normal_300-FXIQ6PXP.ac45821f.woff2 — 36.1 KiB — 0 ms — font-display: swaphttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_italic_normal_400-TZQK3LIS.83ec3132.woff2helveticanowtext_italic... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_italic_normal_400-TZQK3LIS.83ec3132.woff2 — 37.0 KiB — 0 ms — font-display: swaphttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_italic_normal_300-XNHAC4PX.0a09d045.woff2helveticanowtext_italic... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_italic_normal_300-XNHAC4PX.0a09d045.woff2 — 38.7 KiB — 0 ms — font-display: swaphttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_condensed_700-RCQKM25A.c7a15564.woff2helveticanowtext_normal... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_condensed_700-RCQKM25A.c7a15564.woff2 — 60.9 KiB — 0 ms — font-display: swaphttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_condensed_500-36I4O7G3.e062f594.woff2helveticanowtext_normal... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_condensed_500-36I4O7G3.e062f594.woff2 — 60.7 KiB — 0 ms — font-display: swaphttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_condensed_400-M2EPOEX7.c163dd6a.woff2helveticanowtext_normal... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_condensed_400-M2EPOEX7.c163dd6a.woff2 — 57.6 KiB — 0 ms — font-display: swaphttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_condensed_300-M3TV7L3J.602eb597.woff2helveticanowtext_normal... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_normal_condensed_300-M3TV7L3J.602eb597.woff2 — 57.5 KiB — 0 ms — font-display: swaphttps://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_italic_condensed_300-YPWL2OVS.d18585c7.woff2helveticanowtext_italic... https://static.zara.net/stdstatic/8.10.0/js/static/media/helveticanowtext_italic_condensed_300-YPWL2OVS.d18585c7.woff2 — 63.2 KiB — 0 ms — font-display: swap
helveticanowtext_normal... woff2 swap
Size 35 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
helveticanowtext_normal... woff2 swap
Size 36 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
helveticanowtext_normal... woff2 swap
Size 35 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
helveticanowtext_normal... woff2 swap
Size 36 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
helveticanowtext_italic... woff2 swap
Size 37 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
helveticanowtext_italic... woff2 swap
Size 39 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
helveticanowtext_normal... woff2 swap
Size 61 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
helveticanowtext_normal... woff2 swap
Size 61 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
helveticanowtext_normal... woff2 swap
Size 58 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
helveticanowtext_normal... woff2 swap
Size 58 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
helveticanowtext_italic... woff2 swap
Size 63 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
Network Waterfall
108 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
51% of JavaScript execution is third-party
First-party Third-party 1000ms · 1013KB · €11/mo
Unattributable
Other
Costly
Execution 319ms
Transfer 0 KB
Monthly Cost €3/mo
Google Tag Manager
Tag Manager
Costly
Execution 201ms
Transfer 169 KB
Unused 37%
Monthly Cost €2/mo
bdyoomvaq5bp.eu.wpi.jscrambler.com
Other
Optional
Execution 96ms
Transfer 90 KB
Unused 43%
Monthly Cost €1/mo
static.zara.net
Other
Optional
Execution 94ms
Transfer 242 KB
Unused 62%
Monthly Cost €1/mo
static.zara.net
Other
Optional
Execution 90ms
Transfer 104 KB
Unused 35%
Monthly Cost €1/mo
OneTrust
Consent
Essential
Execution 83ms
Transfer 124 KB
Unused 52%
Monthly Cost €1/mo
Google Tag Manager
Tag Manager
Optional
Execution 64ms
Transfer 143 KB
Unused 46%
Monthly Cost €1/mo
Google Tag Manager
Tag Manager
Optional
Execution 53ms
Transfer 141 KB
Unused 43%
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • Unattributable adds 319ms and costs ~€3/month
  • Google Tag Manager adds 201ms and costs ~€2/month

51% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

Learn more ▾

Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

Unattributable takes 319ms 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

Google Tag Manager takes 201ms 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

62% of static.zara.net'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

52% of OneTrust'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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