Performance
· 15 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.
2.33 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
5.34 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
700 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.300
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
5.99 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.
7.55 s
Page Load Progression
1.5 s
2.9 s 4.4 s
5.8 s 7.3 s
8.8 s
10.2 s
11.7 sFPage Weight BudgetAction16.1 MB transferred, 268 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 CostAction6528ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://www.ntv.co.jp/_next/static/chunks/0hmk6a1as_awo.js | 1971ms | 679ms | 8ms | 3rd |
| https://www.ntv.co.jp/_next/static/chunks/0gnsf_stitlnd.js | 1603ms | 215ms | 24ms | 3rd |
| https://www.ntv.co.jp/ | 1522ms | 73ms | 3ms | 3rd |
| Unattributable | 618ms | 22ms | 0ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-TBHL2WG | 289ms | 247ms | 23ms | 3rd |
| https://www.ntv.co.jp/assets/shared/js/ntv.plain.js | 138ms | 76ms | 48ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-W0MEVFFF32&cx=c>m=4e64k0 | 127ms | 73ms | 14ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-780061757&cx=c>m=4e64k0 | 111ms | 96ms | 13ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-KRXX8P7W8P&cx=c>m=4e64k0 | 90ms | 69ms | 15ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-MTZFHCT&l=itm_dl1_1004026 | 59ms | 43ms | 11ms | 3rd |
DJS BundlesAction39 scripts, 463 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 (44%) | ✓ | 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 | 53 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 (45%) | ✓ | 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 InventoryAction268 resources · 16.1 MB · 463 KB savings availableFIX
~462.5 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 268 resources | 16.1 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization112 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 Loading65 fonts (1577 KB)PASS
Web fonts
65
1577 KB total
Render-blocking
0
of 65
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 HintsNo optimization neededPASS
Network Waterfall268 requests over 9464msINFO
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 | 1971ms | 66 KB | 35% | ¥2724/mo | Costly |
www.ntv.co.jp www.ntv.co.jp | Other | 1603ms | 183 KB | 44% | ¥2214/mo | Costly |
www.ntv.co.jp www.ntv.co.jp | Other | 1522ms | 9 KB | — | ¥2104/mo | Costly |
Unattributable Unattributable | Other | 618ms | 0 KB | — | ¥854/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 289ms | 182 KB | 27% | ¥399/mo | Costly |
www.ntv.co.jp www.ntv.co.jp | Other | 138ms | 80 KB | 45% | ¥190/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 127ms | 153 KB | 42% | ¥176/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 111ms | 146 KB | 36% | ¥154/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 90ms | 152 KB | 42% | ¥124/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 59ms | 116 KB | 57% | ¥81/mo | Costly |
These scripts may cost more than they're worth
- www.ntv.co.jp adds 1971ms and costs ~¥2724/month
- www.ntv.co.jp adds 1603ms and costs ~¥2214/month
- www.ntv.co.jp adds 1522ms and costs ~¥2104/month
- Unattributable adds 618ms and costs ~¥854/month
- Google Tag Manager adds 289ms and costs ~¥399/month
- www.ntv.co.jp adds 138ms and costs ~¥190/month
- Google Tag Manager adds 127ms and costs ~¥176/month
- Google Tag Manager adds 111ms and costs ~¥154/month
- Google Tag Manager adds 90ms and costs ~¥124/month
- Google Tag Manager adds 59ms and costs ~¥81/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 1971ms 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 1603ms 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 1522ms 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 618ms 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 289ms 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 138ms 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 127ms 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 111ms 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 90ms 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 59ms 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