Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

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

Mobile Desktop

Performance

Accessibility

Best Practices

100

SEO

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

2.46 s

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

5.14 s

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

57 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.133

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

3.75 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.

8.39 s

Page Load Progression

672 ms

1.3 s

2.0 s

2.7 s

3.4 s

4.0 s

4.7 s

5.4 s

Checks

5 PASS 3 REVIEW 5 FIX

Page Weight Budget

Action

9.5 MB transferred, 285 requests

FIX

9.5 MB transferred, 285 requests

Page weighs 16.0 MB (9.5 MB transferred)

Images are 6.8 MB — compress or use modern formats

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Got: 6.8 MB

JavaScript is 2.4 MB — consider code splitting or lazy loading

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Got: 2.4 MB

285 HTTP requests — consider bundling or reducing

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Estimated 2.0 g CO2 per page load

9.5 MB transferred

285 requests

2.0 g CO2 per page load

Images 6.8 MiB 71%

JavaScript 2.4 MiB 26%

Other 119.3 KiB 1%

Fonts 70.9 KiB 1%

CSS 50.3 KiB 1%

HTML 25.5 KiB 0%

Other 17.2 KiB 0%

Other 15.4 KiB 0%

Other 4.6 KiB 0%

Other 0 B 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

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

Third-Party Impact

Action

100% third-party, 0 ms blocking

FIX

100% third-party, 0 ms blocking

Third-party code accounts for 100% of page weight (9.5 MiB of 9.5 MiB)

Third-party blocking time is low (0 ms)

100%

First-party Third-party

JS Bundles

Action

64 scripts, 868 KB unused

FIX

64 scripts, 868 KB unused

https://www.googletagmanager.com/gtag/destination?...: 69 KB unused (48%)

Consider code splitting or tree shaking to reduce unused code.

https://www.googletagmanager.com/gtag/destination?...: 68 KB unused (47%)

Consider code splitting or tree shaking to reduce unused code.

https://assets.adobedtm.com/17361013af29ef6ae83ffd...: 68 KB unused (25%)

Consider code splitting or tree shaking to reduce unused code.

https://www.so-net.ne.jp/assets/scripts/emergency....: 66 KB unused (35%)

Consider code splitting or tree shaking to reduce unused code.

https://www.googletagmanager.com/gtag/js?id=UA-355...: 64 KB unused (51%)

Consider code splitting or tree shaking to reduce unused code.

Total unused JavaScript: 868 KB

868 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://www.googletagmanager.com/gtag/destination?id=AW-1056115045&cx=c&gtm=4e64h1	145 KB	69 KB (48%)	✓	3rd
https://www.googletagmanager.com/gtag/destination?id=AW-11036283457&cx=c&gtm=4e64h1	145 KB	68 KB (47%)	✓	3rd
https://assets.adobedtm.com/17361013af29ef6ae83ffd4113ce414f44be89b8/satelliteLib-ea3bae92bad6869bca2ee96094be75c242840f35.js	275 KB	68 KB (25%)	✓	3rd
https://www.so-net.ne.jp/assets/scripts/emergency.js	191 KB	66 KB (35%)	✓	3rd
https://www.googletagmanager.com/gtag/js?id=UA-35505952-6	125 KB	64 KB (51%)	✓	3rd
https://www.googletagmanager.com/gtag/js?id=G-FFF2L11TTY&cx=c&gtm=4e64h1	158 KB	63 KB (40%)	✓	3rd
https://www.googletagmanager.com/gtag/js?id=G-LFLR66P29B&cx=c&gtm=4e64h1	146 KB	62 KB (42%)	✓	3rd
https://www.googletagmanager.com/gtag/js?id=DC-9591676	129 KB	60 KB (47%)	✓	3rd
https://www.googletagmanager.com/gtag/js?id=AW-17958994411&cx=c&gtm=4e64h1	137 KB	60 KB (44%)	✓	3rd
https://ce.mf.marsflag.com/v1/js/mf-search.js	110 KB	57 KB (52%)	✓	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

Page Weight Inventory

Action

285 resources · 9.5 MB · 868 KB savings available

FIX

285 resources · 9.5 MB · 868 KB savings available

Page weight 8.5 MB over 1MB target

Got: 9.5 MB Expected: ≤ 1 MB

~868 KB of savings available

284 third-party resources (100% of weight)

6 resources over 200KB

285 resources · 9.5 MiB · 284 third-party 8.5 MiB over 1MB target

Image 71% · 6.8 MiB

JavaScript 26% · 2.5 MiB

Other 1% · 90.7 KiB

Font 1% · 70.9 KiB

CSS 1% · 50.3 KiB

Document 0% · 27.3 KiB

~868.1 KiB of savings available

Remove unused JavaScript: 868.1 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

285 resources			9.5 MiB

HTTP Caching

Action

No cache headers

FIX

No cache headers

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.

Image Optimization

Action

138 images, 0 KB saveable

REVIEW

138 images, 0 KB saveable

https://www.so-net.ne.jp/_system/img/icon_ipvx.png... is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

https://img-cf.karte.io/image/67bfd2e801d618be9080... is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

https://www.so-net.ne.jp/gspm7r00000007r3-img/thum... is missing width/height — may cause layout shift

Set explicit width and height to prevent CLS.

138 images 6.8 MB

0 oversized -0 KB

136 legacy format

3 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

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

Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.

Source: web.dev / Core Web Vitals

JS Execution Cost

Action

1966ms total JS execution

REVIEW

1966ms total JS execution

https://www.so-net.ne.jp/: 584ms CPU time

Unattributable: 392ms CPU time

https://assets.adobedtm.com/17361013af29ef6ae83ffd...: 186ms CPU time

https://www.so-net.ne.jp/assets/scripts/common.js: 184ms CPU time

https://www.googletagmanager.com/gtm.js?id=GTM-5QL...: 103ms CPU time

Third-party scripts: 1966ms (100% of total)

Main Thread Breakdown

Script Evaluation 49% Style & Layout 23% Other 17% Script Parsing & Compilation 6%

Script	Total	Scripting	Parse/Compile	Party
https://www.so-net.ne.jp/	584ms	20ms	1ms	3rd
Unattributable	392ms	37ms	0ms	3rd
https://assets.adobedtm.com/17361013af29ef6ae83ffd4113ce414f44be89b8/satelliteLib-ea3bae92bad6869bca2ee96094be75c242840f35.js	186ms	145ms	29ms	3rd
https://www.so-net.ne.jp/assets/scripts/common.js	184ms	53ms	4ms	3rd
https://www.googletagmanager.com/gtm.js?id=GTM-5QL4TN8	103ms	84ms	15ms	3rd
https://www.so-net.ne.jp/assets/scripts/emergency.js	99ms	95ms	1ms	3rd
https://bs.karte.io/action/__widget-v2-action/latest/index.js	81ms	70ms	0ms	3rd
https://cdn-edge.karte.io/__edge_plugins/context_event/index.js	77ms	75ms	0ms	3rd
https://connect.facebook.net/signals/config/1288877828691592?v=2.9.303&r=stable&domain=www.so-net.ne.jp&hme=97937018cefade17726f0472876fc101316b2ce9008a35a6a5a7977d7436151a&ex_m=104%2C205%2C154%2C22%2C72%2C73%2C145%2C68%2C67%2C11%2C162%2C90%2C16%2C138%2C127%2C39%2C75%2C78%2C134%2C159%2C164%2C8%2C4%2C5%2C7%2C6%2C3%2C91%2C101%2C165%2C170%2C219%2C62%2C186%2C187%2C55%2C276%2C30%2C74%2C231%2C230%2C229%2C23%2C33%2C103%2C61%2C10%2C63%2C97%2C98%2C99%2C105%2C130%2C31%2C29%2C132%2C133%2C129%2C128%2C155%2C76%2C158%2C156%2C157%2C50%2C60%2C123%2C15%2C161%2C45%2C263%2C264%2C262%2C26%2C27%2C28%2C48%2C146%2C77%2C112%2C18%2C20%2C44%2C40%2C42%2C41%2C83%2C92%2C96%2C110%2C144%2C147%2C46%2C111%2C24%2C21%2C119%2C69%2C36%2C149%2C148%2C150%2C141%2C139%2C25%2C35%2C59%2C109%2C160%2C70%2C17%2C152%2C114%2C81%2C66%2C19%2C85%2C86%2C116%2C84%2C136%2C135%2C34%2C278%2C293%2C212%2C201%2C202%2C200%2C296%2C288%2C52%2C213%2C107%2C131%2C80%2C121%2C54%2C47%2C49%2C113%2C120%2C126%2C58%2C64%2C151%2C115%2C37%2C32%2C53%2C56%2C100%2C163%2C1%2C124%2C14%2C122%2C12%2C2%2C57%2C93%2C65%2C118%2C89%2C88%2C166%2C167%2C94%2C95%2C9%2C125%2C102%2C51%2C142%2C87%2C79%2C71%2C117%2C106%2C43%2C143%2C0%2C82%2C137%2C140%2C153%2C38%2C108%2C13%2C168	73ms	64ms	8ms	3rd
https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwMA.js	69ms	52ms	8ms	3rd

Showing top 10 of 12 scripts

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

All text resources are properly compressed.

A+

Font Loading

1 fonts (71 KB)

PASS

1 fonts (71 KB)

1 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

71 KB total

Render-blocking

of 1

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

fontawesome-webfont.woff2 unknown swap

Size 71 KB

Load time 307 ms

Start 3.7 s

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)

Fixing the unchecked items could save ~21 KB and ~42 ms

A+

Resource Caching

All resources properly cached

PASS

All resources properly cached

No caching issues found

All static resources have appropriate caching headers.

A+

Critical Rendering Path

No render-blocking resources

PASS

No render-blocking resources

No render-blocking resources detected

A+

Resource Hints

No optimization needed

PASS

No optimization needed

No resource hint issues

Network Waterfall

285 requests over 5890ms

INFO

HTML JavaScript CSS Images Fonts XHR/Fetch Other

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 1966ms · 1318KB · ¥2717/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
www.so-net.ne.jp www.so-net.ne.jp	Other	584ms	15 KB	—	¥806/mo	Costly
Unattributable Unattributable	Other	392ms	0 KB	—	¥542/mo	Costly
assets.adobedtm.com assets.adobedtm.com	Other	186ms	275 KB	25%	¥257/mo	Costly
www.so-net.ne.jp www.so-net.ne.jp	Other	184ms	33 KB	—	¥254/mo	Costly
Google Tag Manager www.googletagmanager.com	Tag Manager	103ms	166 KB	31%	¥143/mo	Costly
www.so-net.ne.jp www.so-net.ne.jp	Other	99ms	191 KB	35%	¥137/mo	Costly
bs.karte.io bs.karte.io	Other	81ms	77 KB	42%	¥112/mo	Costly
cdn-edge.karte.io cdn-edge.karte.io	Other	77ms	27 KB	—	¥106/mo	Costly
Facebook Pixel connect.facebook.net	Advertising	73ms	125 KB	29%	¥101/mo	Costly
analytics.tiktok.com analytics.tiktok.com	Other	69ms	106 KB	53%	¥95/mo	Costly
Google Tag Manager www.googletagmanager.com	Tag Manager	69ms	158 KB	40%	¥95/mo	Costly
Google Tag Manager www.googletagmanager.com	Tag Manager	50ms	145 KB	47%	¥70/mo	Costly

www.so-net.ne.jp

Other

Costly

Execution 584ms

Transfer 15 KB

Monthly Cost ¥806/mo

Unattributable

Other

Costly

Execution 392ms

Transfer 0 KB

Monthly Cost ¥542/mo

assets.adobedtm.com

Other

Costly

Execution 186ms

Transfer 275 KB

Unused 25%

Monthly Cost ¥257/mo

www.so-net.ne.jp

Other

Costly

Execution 184ms

Transfer 33 KB

Monthly Cost ¥254/mo

Google Tag Manager

Tag Manager

Costly

Execution 103ms

Transfer 166 KB

Unused 31%

Monthly Cost ¥143/mo

www.so-net.ne.jp

Other

Costly

Execution 99ms

Transfer 191 KB

Unused 35%

Monthly Cost ¥137/mo

bs.karte.io

Other

Costly

Execution 81ms

Transfer 77 KB

Unused 42%

Monthly Cost ¥112/mo

cdn-edge.karte.io

Other

Costly

Execution 77ms

Transfer 27 KB

Monthly Cost ¥106/mo

Facebook Pixel

Advertising

Costly

Execution 73ms

Transfer 125 KB

Unused 29%

Monthly Cost ¥101/mo

analytics.tiktok.com

Other

Costly

Execution 69ms

Transfer 106 KB

Unused 53%

Monthly Cost ¥95/mo

Google Tag Manager

Tag Manager

Costly

Execution 69ms

Transfer 158 KB

Unused 40%

Monthly Cost ¥95/mo

Google Tag Manager

Tag Manager

Costly

Execution 50ms

Transfer 145 KB

Unused 47%

Monthly Cost ¥70/mo

These scripts may cost more than they're worth

www.so-net.ne.jp adds 584ms and costs ~¥806/month
Unattributable adds 392ms and costs ~¥542/month
assets.adobedtm.com adds 186ms and costs ~¥257/month
www.so-net.ne.jp adds 184ms and costs ~¥254/month
Google Tag Manager adds 103ms and costs ~¥143/month
www.so-net.ne.jp adds 99ms and costs ~¥137/month
bs.karte.io adds 81ms and costs ~¥112/month
cdn-edge.karte.io adds 77ms and costs ~¥106/month
Facebook Pixel adds 73ms and costs ~¥101/month
analytics.tiktok.com adds 69ms and costs ~¥95/month
Google Tag Manager adds 69ms and costs ~¥95/month
Google Tag Manager adds 50ms and costs ~¥70/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

www.so-net.ne.jp takes 584ms 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 392ms 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

assets.adobedtm.com takes 186ms 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

www.so-net.ne.jp takes 184ms 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 103ms 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

www.so-net.ne.jp takes 99ms 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

bs.karte.io takes 81ms 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

cdn-edge.karte.io takes 77ms 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

Facebook Pixel takes 73ms 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

analytics.tiktok.com takes 69ms 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

53% of analytics.tiktok.com'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

Google Tag Manager takes 69ms 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 50ms 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.