Performance
· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
4.16 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
36.13 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
6.70 s
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.284
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
18.12 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.
36.83 s
Page Load Progression
1.4 s 2.7 s
4.1 s 5.4 s
6.8 s
8.1 s
9.5 s
10.8 sFPage Weight BudgetAction15.1 MB transferred, 263 requestsFIX
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.
Source: web.dev
Subset fonts to include only used characters, or switch to system font stacks.
Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).
Source: web.dev font loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
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.
High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.
Source: web.dev
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
FJS Execution CostAction30873ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.ntv.co.jp/_next/static/chunks/0gnsf_stitlnd.js | 9230ms | 1114ms | 77ms | 3rd |
| https://www.ntv.co.jp/_next/static/chunks/0hmk6a1as_awo.js | 8571ms | 3074ms | 31ms | 3rd |
| https://www.ntv.co.jp/ | 6928ms | 248ms | 11ms | 3rd |
| Unattributable | 2368ms | 129ms | 0ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-TBHL2WG | 1031ms | 887ms | 94ms | 3rd |
| https://www.ntv.co.jp/assets/shared/js/ntv.plain.js | 531ms | 291ms | 199ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-KRXX8P7W8P&cx=c>m=4e64k0 | 523ms | 290ms | 58ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-780061757&cx=c>m=4e64k0 | 434ms | 376ms | 51ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-W0MEVFFF32&cx=c>m=4e64k0 | 334ms | 266ms | 56ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-MTZFHCT&l=itm_dl1_1004026 | 307ms | 184ms | 44ms | 3rd |
Showing top 10 of 16 scripts
DJS BundlesAction39 scripts, 461 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.ntv.co.jp/_next/static/chunks/0gnsf_stitlnd.js | 183 KB | 79 KB (43%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-MTZFHCT&l=itm_dl1_1004026 | 116 KB | 67 KB (57%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-W0MEVFFF32&cx=c>m=4e64k0 | 153 KB | 64 KB (42%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-KRXX8P7W8P&cx=c>m=4e64k0 | 152 KB | 64 KB (42%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-780061757&cx=c>m=4e64k0 | 146 KB | 52 KB (36%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-TBHL2WG | 182 KB | 50 KB (27%) | ✓ | 3rd |
| https://www.ntv.co.jp/assets/shared/js/ntv.plain.js | 80 KB | 35 KB (44%) | ✓ | 3rd |
| https://www.ntv.co.jp/_next/static/chunks/0w4uzpdbjshyi.js | 46 KB | 28 KB (61%) | ✓ | 3rd |
| https://www.ntv.co.jp/_next/static/chunks/0hmk6a1as_awo.js | 66 KB | 23 KB (35%) | ✓ | 3rd |
| https://static.ads-twitter.com/uwt.js | 13 KB | — | ✓ | 3rd |
Consider code splitting or tree shaking to reduce unused code.
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.
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.
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.
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.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
FPage Weight InventoryAction263 resources · 15.1 MB · 461 KB savings availableFIX
~460.8 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 263 resources | 15.1 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization108 images, 0 KB saveableREVIEW
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
A+Text CompressionAll text resources are compressedPASS
A+Font Loading64 fonts (1572 KB)PASS
Web fonts
64
1572 KB total
Render-blocking
0
of 64
Dominant font-display
swap
Most common across fonts
Font loading timeline
- Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
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 ~107 KB and ~214 ms
A+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource Hints4 hints, 0 missing preconnectsPASS
Current Resource Hints
4 resource hints configured
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
Network Waterfall263 requests over 9805msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
www.ntv.co.jp www.ntv.co.jp | Other | 9230ms | 183 KB | 43% | ¥12754/mo | Costly |
www.ntv.co.jp www.ntv.co.jp | Other | 8571ms | 66 KB | 35% | ¥11843/mo | Costly |
www.ntv.co.jp www.ntv.co.jp | Other | 6928ms | 8 KB | — | ¥9573/mo | Costly |
Unattributable Unattributable | Other | 2368ms | 0 KB | — | ¥3272/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 1031ms | 182 KB | 27% | ¥1425/mo | Costly |
www.ntv.co.jp www.ntv.co.jp | Other | 531ms | 80 KB | 44% | ¥733/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 523ms | 152 KB | 42% | ¥722/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 434ms | 146 KB | 36% | ¥600/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 334ms | 153 KB | 42% | ¥462/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 307ms | 116 KB | 57% | ¥425/mo | Costly |
cdn.cxense.com cdn.cxense.com | Other | 271ms | 38 KB | — | ¥374/mo | Costly |
Google Analytics www.google-analytics.com | Analytics | 97ms | 21 KB | — | ¥134/mo | Costly |
Twitter/X Pixel static.ads-twitter.com | Advertising | 85ms | 13 KB | — | ¥118/mo | Costly |
dmp.im-apps.net dmp.im-apps.net | Other | 61ms | 23 KB | — | ¥84/mo | Costly |
dev.visualwebsiteoptimizer.com dev.visualwebsiteoptimizer.com | Other | 52ms | 5 KB | — | ¥71/mo | Costly |
www.ntv.co.jp www.ntv.co.jp | Other | 51ms | 80 KB | — | ¥70/mo | Costly |
These scripts may cost more than they're worth
- www.ntv.co.jp adds 9230ms and costs ~¥12754/month
- www.ntv.co.jp adds 8571ms and costs ~¥11843/month
- www.ntv.co.jp adds 6928ms and costs ~¥9573/month
- Unattributable adds 2368ms and costs ~¥3272/month
- Google Tag Manager adds 1031ms and costs ~¥1425/month
- www.ntv.co.jp adds 531ms and costs ~¥733/month
- Google Tag Manager adds 523ms and costs ~¥722/month
- Google Tag Manager adds 434ms and costs ~¥600/month
- Google Tag Manager adds 334ms and costs ~¥462/month
- Google Tag Manager adds 307ms and costs ~¥425/month
- cdn.cxense.com adds 271ms and costs ~¥374/month
- Google Analytics adds 97ms and costs ~¥134/month
- Twitter/X Pixel adds 85ms and costs ~¥118/month
- dmp.im-apps.net adds 61ms and costs ~¥84/month
- dev.visualwebsiteoptimizer.com adds 52ms and costs ~¥71/month
- www.ntv.co.jp adds 51ms and costs ~¥70/month
100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.
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.ntv.co.jp takes 9230ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.ntv.co.jp takes 8571ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.ntv.co.jp takes 6928ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Unattributable takes 2368ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 1031ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.ntv.co.jp takes 531ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 523ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 434ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 334ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 307ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
57% of Google Tag Manager's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
cdn.cxense.com takes 271ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Analytics takes 97ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Twitter/X Pixel takes 85ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
dmp.im-apps.net takes 61ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
dev.visualwebsiteoptimizer.com takes 52ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.ntv.co.jp takes 51ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev