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https://zalo.me

Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
77
GRADE
C
FIX
4
REVIEW
3
PASS
6
INFO
2

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

Mobile Desktop
59
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.
100
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.

3.86 s

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

4.24 s

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

1 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.

5.75 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.

5.25 s

Page Load Progression

1.4 s
2.8 s
4.2 s
5.6 s
7.0 s
8.4 s
9.8 s
11.2 s
Checks
15
6 PASS 3 REVIEW 4 FIX
F
Page Weight Budget
Action
6.1 MB transferred, 44 requests
FIX
6.1 MB transferred, 44 requests
Critical::
Page weighs 7.8 MB (6.1 MB transferred)
Warning::
Images are 1.3 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 1.3 MB
Info::
44 HTTP requests
Info::
Estimated 1.3 g CO2 per page load
6.1 MB / 2.4 MB budget
6.1 MB transferred
44 requests
1.3 g CO2 per page load
Other 4.2 MiB 69%
Images 1.3 MiB 21%
JavaScript 498.7 KiB 8%
HTML 59.3 KiB 1%
Fonts 53.2 KiB 1%
CSS 6.8 KiB 0%
Other 3.1 KiB 0%
Other 1.2 KiB 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

D
Third-Party Impact
Action
99% third-party, 0 ms blocking
FIX
99% third-party, 0 ms blocking
Warning::
Third-party code accounts for 99% of page weight (6.0 MiB of 6.1 MiB)
Info::
Third-party blocking time is low (0 ms)
99%
First-party Third-party
D
Page Weight Inventory
Action
44 resources · 6.1 MB · 281 KB savings available
FIX
44 resources · 6.1 MB · 281 KB savings available
Warning::
Page weight 5.1 MB over 1MB target
Got: 6.1 MB Expected: ≤ 1 MB
Info::
~281 KB of savings available
Warning::
35 third-party resources (99% of weight)
Info::
4 resources over 200KB
44 resources · 6.1 MiB · 35 third-party 5.1 MiB over 1MB target
Media 69% · 4.2 MiB
Image 21% · 1.3 MiB
JavaScript 8% · 498.7 KiB
Document 1% · 60.3 KiB
Font 1% · 53.2 KiB
CSS 0% · 6.8 KiB
Other 0% · 3.3 KiB

~281.1 KiB of savings available

Remove unused JavaScript: 281.1 KiB
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
JS Execution Cost
802ms total JS execution
REVIEW
802ms total JS execution
Warning::
https://zalo-site.zadn.vn/_next/static/chunks/72-e...: 452ms CPU time
Info::
Unattributable: 136ms CPU time
Info::
https://zalo.me/vi/: 126ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-YT9T...: 87ms CPU time
Warning::
Third-party scripts: 675ms (84% of total)

Main Thread Breakdown

Script Evaluation 56% Other 24% Script Parsing & Compilation 8% Style & Layout 7%
ScriptTotalScriptingParse/CompileParty
https://zalo-site.zadn.vn/_next/static/chunks/72-e99d024120ffd053.js452ms368ms9ms3rd
Unattributable136ms6ms0ms3rd
https://zalo.me/vi/126ms8ms11ms1st
https://www.googletagmanager.com/gtag/js?id=G-YT9TMXZYV987ms70ms16ms3rd
C
JS Bundles
Action
11 scripts, 281 KB unused
REVIEW
11 scripts, 281 KB unused
Warning::
https://zalo-site.zadn.vn/_next/static/chunks/3e0b...: 180 KB unused (100%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-YT9T...: 65 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://zalo-site.zadn.vn/_next/static/chunks/72-e...: 36 KB unused (54%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 281 KB
281 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://zalo-site.zadn.vn/_next/static/chunks/3e0b8747-36ab4d2ef4aeb483.js180 KB180 KB (100%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-YT9TMXZYV9157 KB65 KB (42%)✓3rd
https://zalo-site.zadn.vn/_next/static/chunks/72-e99d024120ffd053.js67 KB36 KB (54%)✓3rd
https://zalo-site.zadn.vn/_next/static/chunks/webpack-e1e679bd9f97c66f.js2 KB—✓3rd
https://zalo-site.zadn.vn/_next/static/chunks/3d0c8858-c27fefb9802814e8.js53 KB—✓3rd
https://zalo-site.zadn.vn/_next/static/chunks/main-app-379f88342272c63c.js0 KB—✓3rd
https://zalo-site.zadn.vn/_next/static/chunks/361-71bfcec8f61d83f7.js22 KB—✓3rd
https://zalo-site.zadn.vn/_next/static/chunks/541-1abf66933ff78e9d.js6 KB—✓3rd
https://zalo-site.zadn.vn/_next/static/chunks/867-bf530d18c8d86b6d.js5 KB—✓3rd
https://zalo-site.zadn.vn/_next/static/chunks/app/%5Blocale%5D/layout-8ff649a6ec709a68.js4 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

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

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
Image Optimization
17 images, 0 KB saveable
PASS
17 images, 0 KB saveable
Info::
All images are well-optimized
17 images 1.3 MB
0 oversized -0 KB
2 legacy format
0 missing dimensions CLS risk
A+
Font Loading
1 fonts (53 KB)
PASS
1 fonts (53 KB)
Info::
1 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

1

53 KB total

Render-blocking

0

of 1

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 4.0 s 5.0 s 6.0 s 7.0 s FCP 3.9 s LCP 4.2 shttps://zalo-site.zadn.vn/fonts/Gilroy%20Medium.otfGilroy%20Medium.otf https://zalo-site.zadn.vn/fonts/Gilroy%20Medium.otf — 53.2 KiB — 1.9 s — font-display: swap
Gilroy%20Medium.otf otf swap
Size 53 KB
Load time 1.9 s
Start 4.8 s
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 ~16 KB and ~32 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
Network Waterfall
44 requests over 9310ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s 8.0 s 9.0 s FCP 3.9 s LCP 4.2 shttps://zalo.me// https://zalo.me/ — 307 — 150 B — 2.0 s — h2https://zalo.me/vi//vi/ https://zalo.me/vi/ — 200 — 59.3 KiB — 4.0 s — h2https://zalo-site.zadn.vn/_next/static/media/home-banner.20ff632e.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/home-banner.20ff632e.webp — 200 — 196.9 KiB — 3.9 s — h2https://zalo-site.zadn.vn/_next/static/css/50d32ac218e5ffc7.csszalo-site.zadn.vn/_next/static/css/... https://zalo-site.zadn.vn/_next/static/css/50d32ac218e5ffc7.css — 200 — 6.8 KiB — 2.4 s — h2https://www.googletagmanager.com/gtag/js?id=G-YT9TMXZYV9www.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-YT9TMXZYV9 — 200 — 157.3 KiB — 244 ms — h2https://zalo-site.zadn.vn/_next/static/media/home-vi-thumb.24175e4a.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/home-vi-thumb.24175e4a.webp — 200 — 21.2 KiB — 2.8 s — h2https://zalo-site.zadn.vn/_next/static/chunks/webpack-e1e679bd9f97c66f.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/webpack-e1e679bd9f97c66f.js — 200 — 1.9 KiB — 4.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/3d0c8858-c27fefb9802814e8.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/3d0c8858-c27fefb9802814e8.js — 200 — 53.1 KiB — 4.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/3e0b8747-36ab4d2ef4aeb483.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/3e0b8747-36ab4d2ef4aeb483.js — 200 — 179.7 KiB — 4.1 s — h2https://zalo-site.zadn.vn/_next/static/media/zalo-video-thumb.f3fb629e.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/zalo-video-thumb.f3fb629e.webp — 200 — 8.6 KiB — 1.6 s — h2https://zalo-site.zadn.vn/_next/static/chunks/72-e99d024120ffd053.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/72-e99d024120ffd053.js — 200 — 67.0 KiB — 2.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/main-app-379f88342272c63c.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/main-app-379f88342272c63c.js — 200 — 355 B — 2.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/361-71bfcec8f61d83f7.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/361-71bfcec8f61d83f7.js — 200 — 21.7 KiB — 2.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/541-1abf66933ff78e9d.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/541-1abf66933ff78e9d.js — 200 — 5.9 KiB — 2.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/867-bf530d18c8d86b6d.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/867-bf530d18c8d86b6d.js — 200 — 4.8 KiB — 2.3 s — h2https://zalo-site.zadn.vn/_next/static/chunks/app/%5Blocale%5D/layout-8ff649a6ec709a68.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/app/%5Blocale%5D/layout-8ff649a6ec709a68.js — 200 — 4.0 KiB — 2.6 s — h2https://zalo-site.zadn.vn/_next/static/chunks/app/%5Blocale%5D/page-2dc14f46fec0db6e.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/app/%5Blocale%5D/page-2dc14f46fec0db6e.js — 200 — 3.0 KiB — 2.6 s — h2https://zalo-site.zadn.vn/videos/home-vi.mp4zalo-site.zadn.vn/videos/home-vi.mp... https://zalo-site.zadn.vn/videos/home-vi.mp4 — 206 — 174.8 KiB — 2.8 s — h2https://zalo-site.zadn.vn/videos/zalo-video-thumb.mp4zalo-site.zadn.vn/videos/zalo-video... https://zalo-site.zadn.vn/videos/zalo-video-thumb.mp4 — 206 — 566.3 KiB — 3.4 s — h2https://zalo-site.zadn.vn/_next/static/media/logo.a68785cd.svgzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/logo.a68785cd.svg — 200 — 1.5 KiB — 1.1 s — h2https://zalo-site.zadn.vn/_next/static/media/globe.df2543e7.svgzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/globe.df2543e7.svg — 200 — 940 B — 1.1 s — h2https://zalo-site.zadn.vn/_next/static/media/zalo-in-action-1.1c93e7b2.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/zalo-in-action-1.1c93e7b2.webp — 200 — 444.6 KiB — 3.5 s — h2https://zalo-site.zadn.vn/_next/static/media/zalo-in-action-2.e3758ed2.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/zalo-in-action-2.e3758ed2.webp — 200 — 40.7 KiB — 3.5 s — h2https://zalo-site.zadn.vn/_next/static/media/zalo-in-action-3.977aeb8b.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/zalo-in-action-3.977aeb8b.webp — 200 — 110.7 KiB — 3.5 s — h2https://zalo-site.zadn.vn/_next/static/media/people.1648f8db.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/people.1648f8db.webp — 200 — 355.4 KiB — 3.9 s — h2https://zalo-site.zadn.vn/_next/static/media/kiki.d715d09c.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/kiki.d715d09c.webp — 200 — 19.4 KiB — 3.9 s — h2https://zalo-site.zadn.vn/_next/static/media/logo-zalo.5eb1a7b1.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/logo-zalo.5eb1a7b1.webp — 200 — 4.5 KiB — 3.9 s — h2https://zalo-site.zadn.vn/_next/static/media/logo-zing-mp3.1e2859e1.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/logo-zing-mp3.1e2859e1.webp — 200 — 5.2 KiB — 3.9 s — h2https://zalo-site.zadn.vn/_next/static/media/logo-bao-moi.1086e2f9.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/logo-bao-moi.1086e2f9.webp — 200 — 4.8 KiB — 3.9 s — h2https://zalo-site.zadn.vn/_next/static/media/logo-kiki.6f994693.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/logo-kiki.6f994693.webp — 200 — 2.0 KiB — 3.9 s — h2
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s 8.0 s 9.0 s FCP 3.9 s LCP 4.2 shttps://zalo.me// https://zalo.me/ — 307 — 150 B — 2.0 s — h2https://zalo.me/vi//vi/ https://zalo.me/vi/ — 200 — 59.3 KiB — 4.0 s — h2https://zalo-site.zadn.vn/_next/static/media/home-banner.20ff632e.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/home-banner.20ff632e.webp — 200 — 196.9 KiB — 3.9 s — h2https://zalo-site.zadn.vn/_next/static/css/50d32ac218e5ffc7.csszalo-site.zadn.vn/_next/static/css/... https://zalo-site.zadn.vn/_next/static/css/50d32ac218e5ffc7.css — 200 — 6.8 KiB — 2.4 s — h2https://www.googletagmanager.com/gtag/js?id=G-YT9TMXZYV9www.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-YT9TMXZYV9 — 200 — 157.3 KiB — 244 ms — h2https://zalo-site.zadn.vn/_next/static/media/home-vi-thumb.24175e4a.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/home-vi-thumb.24175e4a.webp — 200 — 21.2 KiB — 2.8 s — h2https://zalo-site.zadn.vn/_next/static/chunks/webpack-e1e679bd9f97c66f.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/webpack-e1e679bd9f97c66f.js — 200 — 1.9 KiB — 4.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/3d0c8858-c27fefb9802814e8.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/3d0c8858-c27fefb9802814e8.js — 200 — 53.1 KiB — 4.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/3e0b8747-36ab4d2ef4aeb483.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/3e0b8747-36ab4d2ef4aeb483.js — 200 — 179.7 KiB — 4.1 s — h2https://zalo-site.zadn.vn/_next/static/media/zalo-video-thumb.f3fb629e.webpzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/zalo-video-thumb.f3fb629e.webp — 200 — 8.6 KiB — 1.6 s — h2https://zalo-site.zadn.vn/_next/static/chunks/72-e99d024120ffd053.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/72-e99d024120ffd053.js — 200 — 67.0 KiB — 2.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/main-app-379f88342272c63c.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/main-app-379f88342272c63c.js — 200 — 355 B — 2.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/361-71bfcec8f61d83f7.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/361-71bfcec8f61d83f7.js — 200 — 21.7 KiB — 2.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/541-1abf66933ff78e9d.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/541-1abf66933ff78e9d.js — 200 — 5.9 KiB — 2.2 s — h2https://zalo-site.zadn.vn/_next/static/chunks/867-bf530d18c8d86b6d.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/867-bf530d18c8d86b6d.js — 200 — 4.8 KiB — 2.3 s — h2https://zalo-site.zadn.vn/_next/static/chunks/app/%5Blocale%5D/layout-8ff649a6ec709a68.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/app/%5Blocale%5D/layout-8ff649a6ec709a68.js — 200 — 4.0 KiB — 2.6 s — h2https://zalo-site.zadn.vn/_next/static/chunks/app/%5Blocale%5D/page-2dc14f46fec0db6e.jszalo-site.zadn.vn/_next/static/chun... https://zalo-site.zadn.vn/_next/static/chunks/app/%5Blocale%5D/page-2dc14f46fec0db6e.js — 200 — 3.0 KiB — 2.6 s — h2https://zalo-site.zadn.vn/videos/home-vi.mp4zalo-site.zadn.vn/videos/home-vi.mp... https://zalo-site.zadn.vn/videos/home-vi.mp4 — 206 — 174.8 KiB — 2.8 s — h2https://zalo-site.zadn.vn/videos/zalo-video-thumb.mp4zalo-site.zadn.vn/videos/zalo-video... https://zalo-site.zadn.vn/videos/zalo-video-thumb.mp4 — 206 — 566.3 KiB — 3.4 s — h2https://zalo-site.zadn.vn/_next/static/media/logo.a68785cd.svgzalo-site.zadn.vn/_next/static/medi... https://zalo-site.zadn.vn/_next/static/media/logo.a68785cd.svg — 200 — 1.5 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HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
84% of JavaScript execution is third-party
First-party Third-party 675ms · 224KB · ₫39994/mo
zalo-site.zadn.vn
Other
Costly
Execution 452ms
Transfer 67 KB
Unused 54%
Monthly Cost ₫26779/mo
Unattributable
Other
Costly
Execution 136ms
Transfer 0 KB
Monthly Cost ₫8060/mo
Google Tag Manager
Tag Manager
Costly
Execution 87ms
Transfer 157 KB
Unused 42%
Monthly Cost ₫5155/mo

These scripts may cost more than they're worth

  • zalo-site.zadn.vn adds 452ms and costs ~₫26779/month
  • Unattributable adds 136ms and costs ~₫8060/month
  • Google Tag Manager adds 87ms and costs ~₫5155/month

84% 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

zalo-site.zadn.vn takes 452ms 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

54% of zalo-site.zadn.vn'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 136ms 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 87ms 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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