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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
85
GRADE
B
FIX
4
REVIEW
3
PASS
6
INFO
2

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

Mobile Desktop
76
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.
96
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
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.

1.57 s

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

2.99 s

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

19 ms

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

0.055

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

1.59 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.

2.99 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
15
6 PASS 3 REVIEW 4 FIX
D
Page Weight Budget
Action
2.1 MB transferred, 28 requests
FIX
2.1 MB transferred, 28 requests
Info::
Page weighs 4.4 MB (2.1 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
Warning::
JavaScript is 763 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 763 KB
Info::
28 HTTP requests
Info::
Estimated 0.44 g CO2 per page load
2.1 MB / 2.4 MB budget
2.1 MB transferred
28 requests
0.44 g CO2 per page load
Images 1.3 MiB 61%
JavaScript 763.0 KiB 35%
Fonts 39.3 KiB 2%
HTML 19.3 KiB 1%
CSS 7.2 KiB 0%
Other 6.1 KiB 0%
Other 4.4 KiB 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Approaching limit

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

D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (2.1 MiB of 2.1 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
D
Page Weight Inventory
Action
28 resources · 2.1 MB · 240 KB savings available
FIX
28 resources · 2.1 MB · 240 KB savings available
Warning::
Page weight 1.1 MB over 1MB target
Got: 2.1 MB Expected: ≤ 1 MB
Info::
~240 KB of savings available
Warning::
27 third-party resources (100% of weight)
Info::
3 resources over 200KB
28 resources · 2.1 MiB · 27 third-party 1.1 MiB over 1MB target
Image 61% · 1.3 MiB
JavaScript 35% · 763.0 KiB
Font 2% · 39.3 KiB
Document 1% · 19.6 KiB
CSS 0% · 7.2 KiB
Other 0% · 4.4 KiB

~240.0 KiB of savings available

Remove unused JavaScript: 240.0 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.

C
Image Optimization
Action
5 images, 0 KB saveable
REVIEW
5 images, 0 KB saveable
Warning::
https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-404... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-404... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
5 images 1.3 MB
0 oversized -0 KB
5 legacy format
2 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

C
JS Bundles
Action
7 scripts, 240 KB unused
REVIEW
7 scripts, 240 KB unused
Warning::
https://cdn.jsdelivr.net/ghost/portal@~2.68/umd/po...: 91 KB unused (23%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-LCVW...: 66 KB unused (43%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.jsdelivr.net/ghost/sodo-search@~1.8/um...: 54 KB unused (56%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://ilya.grigorik.com/assets/js/app.min.js?v=3...: 28 KB unused (49%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 240 KB
240 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://cdn.jsdelivr.net/ghost/portal@~2.68/umd/portal.min.js436 KB91 KB (23%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-LCVWBFR9YN155 KB66 KB (43%)✓3rd
https://cdn.jsdelivr.net/ghost/sodo-search@~1.8/umd/sodo-search.min.js98 KB54 KB (56%)✓3rd
https://ilya.grigorik.com/assets/js/app.min.js?v=35da3834ca58 KB28 KB (49%)✓3rd
https://ilya.grigorik.com/public/cards.min.js?v=35da3834ca2 KB—✓3rd
https://ilya.grigorik.com/public/member-attribution.min.js?v=35da3834ca2 KB—✓3rd
https://ilya.grigorik.com/public/ghost-stats.min.js?v=35da3834ca13 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

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+
JS Execution Cost
390ms total JS execution
PASS
390ms total JS execution
Info::
https://cdn.jsdelivr.net/ghost/portal@~2.68/umd/po...: 139ms CPU time
Info::
https://ilya.grigorik.com/: 81ms CPU time
Info::
Unattributable: 57ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-LCVW...: 57ms CPU time
Info::
https://ilya.grigorik.com/assets/js/app.min.js?v=3...: 56ms CPU time
Warning::
Third-party scripts: 390ms (100% of total)

Main Thread Breakdown

Script Evaluation 46% Script Parsing & Compilation 17% Other 16% Style & Layout 15% Parse HTML & CSS 3%
ScriptTotalScriptingParse/CompileParty
https://cdn.jsdelivr.net/ghost/portal@~2.68/umd/portal.min.js139ms76ms46ms3rd
https://ilya.grigorik.com/81ms2ms1ms3rd
Unattributable57ms7ms0ms3rd
https://www.googletagmanager.com/gtag/js?id=G-LCVWBFR9YN57ms48ms9ms3rd
https://ilya.grigorik.com/assets/js/app.min.js?v=35da3834ca56ms34ms11ms3rd
A+
Font Loading
1 fonts (39 KB)
PASS
1 fonts (39 KB)
Info::
1 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

1

39 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 FCP 1.6 s LCP 3.0 shttps://fonts.gstatic.com/s/ibmplexsans/v23/zYXzKVElMYYaJe8bpLHnCwDKr932-G7dytD-Dmu1syxeKYbSB4Zh.woff2zYXzKVElMYYaJe8bpLHnCwD... https://fonts.gstatic.com/s/ibmplexsans/v23/zYXzKVElMYYaJe8bpLHnCwDKr932-G7dytD-Dmu1syxeKYbSB4Zh.woff2 — 39.3 KiB — 39 ms — font-display: swap
zYXzKVElMYYaJe8bpLHnCwD... woff2 swap
Size 39 KB
Load time 39 ms
Start 901 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
28 requests over 1400ms
INFO
0 ms 1.0 s 2.0 s 3.0 s FCP 1.6 s LCP 3.0 shttps://igvita.com// https://igvita.com/ — 301 — 189 B — 470 ms — h2https://www.igvita.com/www.igvita.com/ https://www.igvita.com/ — 301 — 190 B — 159 ms — h2https://ilya.grigorik.com/ilya.grigorik.com/ https://ilya.grigorik.com/ — 200 — 19.3 KiB — 11 ms — h2https://fonts.googleapis.com/css2?family=IBM+Plex+Sans:wght@400;500;600;700&display=swapfonts.googleapis.com/css2?family=IB... https://fonts.googleapis.com/css2?family=IBM+Plex+Sans:wght@400;500;600;700&display=swap — 200 — 1.2 KiB — 86 ms — h2https://cdn.jsdelivr.net/ghost/portal@~2.68/umd/portal.min.jscdn.jsdelivr.net/ghost/portal@~2.68... https://cdn.jsdelivr.net/ghost/portal@~2.68/umd/portal.min.js — 200 — 436.2 KiB — 59 ms — h2https://ilya.grigorik.com/public/cards.min.css?v=35da3834cailya.grigorik.com/public/cards.min.... https://ilya.grigorik.com/public/cards.min.css?v=35da3834ca — 200 — 6.0 KiB — 7 ms — h2https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/2022/06/logo.svgstorage.ghost.io/c/d1/ab/d1ab7f97-6... https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/2022/06/logo.svg — 200 — 3.2 KiB — 18 ms — h2https://ilya.grigorik.com/assets/js/app.min.js?v=35da3834cailya.grigorik.com/assets/js/app.min... https://ilya.grigorik.com/assets/js/app.min.js?v=35da3834ca — 200 — 57.6 KiB — 10 ms — h2https://cdn.jsdelivr.net/ghost/sodo-search@~1.8/umd/sodo-search.min.jscdn.jsdelivr.net/ghost/sodo-search@... https://cdn.jsdelivr.net/ghost/sodo-search@~1.8/umd/sodo-search.min.js — 200 — 97.7 KiB — 24 ms — h2https://ilya.grigorik.com/public/cards.min.js?v=35da3834cailya.grigorik.com/public/cards.min.... https://ilya.grigorik.com/public/cards.min.js?v=35da3834ca — 200 — 1.8 KiB — 16 ms — h2https://ilya.grigorik.com/public/member-attribution.min.js?v=35da3834cailya.grigorik.com/public/member-att... https://ilya.grigorik.com/public/member-attribution.min.js?v=35da3834ca — 200 — 1.5 KiB — 14 ms — h2https://ilya.grigorik.com/public/ghost-stats.min.js?v=35da3834cailya.grigorik.com/public/ghost-stat... https://ilya.grigorik.com/public/ghost-stats.min.js?v=35da3834ca — 200 — 12.8 KiB — 14 ms — h2https://www.googletagmanager.com/gtag/js?id=G-LCVWBFR9YNwww.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-LCVWBFR9YN — 200 — 155.4 KiB — 158 ms — h2https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/size/w1080/2022/06/ilya-waist.jpgstorage.ghost.io/c/d1/ab/d1ab7f97-6... https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/size/w1080/2022/06/ilya-waist.jpg — 200 — 134.5 KiB — 17 ms — h2https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/2024/08/risk-sponge.pngstorage.ghost.io/c/d1/ab/d1ab7f97-6... https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/2024/08/risk-sponge.png — 200 — 675.7 KiB — 25 ms — h2https://ilya.grigorik.com/members/api/member/ilya.grigorik.com/members/api/membe... https://ilya.grigorik.com/members/api/member/ — 204 — 214 B — 73 ms — h2https://fonts.gstatic.com/s/ibmplexsans/v23/zYXzKVElMYYaJe8bpLHnCwDKr932-G7dytD-Dmu1syxeKYbSB4Zh.woff2fonts.gstatic.com/s/ibmplexsans/v23... https://fonts.gstatic.com/s/ibmplexsans/v23/zYXzKVElMYYaJe8bpLHnCwDKr932-G7dytD-Dmu1syxeKYbSB4Zh.woff2 — 200 — 39.3 KiB — 39 ms — h3https://igrigorik.ghost.io/ghost/api/content/settings/?key=0199552185a0b8b40738c405baigrigorik.ghost.io/ghost/api/conten... https://igrigorik.ghost.io/ghost/api/content/settings/?key=0199552185a0b8b40738c405ba — 204 — 0 B — 18 ms — h2https://igrigorik.ghost.io/ghost/api/content/tiers/?limit=100&include=monthly_price%2Cyearly_price%2Cbenefits&key=0199552185a0b8b40738c405baigrigorik.ghost.io/ghost/api/conten... https://igrigorik.ghost.io/ghost/api/content/tiers/?limit=100&include=monthly_price%2Cyearly_price%2Cbenefits&key=0199552185a0b8b40738c405ba — 204 — 0 B — 18 ms — h2https://igrigorik.ghost.io/ghost/api/content/newsletters/?limit=100&key=0199552185a0b8b40738c405baigrigorik.ghost.io/ghost/api/conten... https://igrigorik.ghost.io/ghost/api/content/newsletters/?limit=100&key=0199552185a0b8b40738c405ba — 204 — 0 B — 16 ms — h2https://igrigorik.ghost.io/ghost/api/content/newsletters/?limit=100&key=0199552185a0b8b40738c405baigrigorik.ghost.io/ghost/api/conten... https://igrigorik.ghost.io/ghost/api/content/newsletters/?limit=100&key=0199552185a0b8b40738c405ba — 200 — 643 B — 6 ms — h2https://igrigorik.ghost.io/ghost/api/content/settings/?key=0199552185a0b8b40738c405baigrigorik.ghost.io/ghost/api/conten... https://igrigorik.ghost.io/ghost/api/content/settings/?key=0199552185a0b8b40738c405ba — 200 — 2.2 KiB — 8 ms — h2https://igrigorik.ghost.io/ghost/api/content/tiers/?limit=100&include=monthly_price%2Cyearly_price%2Cbenefits&key=0199552185a0b8b40738c405baigrigorik.ghost.io/ghost/api/conten... https://igrigorik.ghost.io/ghost/api/content/tiers/?limit=100&include=monthly_price%2Cyearly_price%2Cbenefits&key=0199552185a0b8b40738c405ba — 200 — 560 B — 6 ms — h2https://region1.google-analytics.com/g/collect?v=2&tid=G-LCVWBFR9YN&gtm=45je64h1v896048868za200zd896048868&_p=1776804586758&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&are=1&cid=671720968.1776804587&frm=0&pscdl=noapi&rcb=19&sr=800x600&uaa=x86&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115938465~115938469~117266400~117512542~118463261&sid=1776804587&sct=1&seg=0&dl=https%3A%2F%2Filya.grigorik.com%2F&dt=Ilya%20Grigorik&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=1029region1.google-analytics.com/g/coll... https://region1.google-analytics.com/g/collect?v=2&tid=G-LCVWBFR9YN&gtm=45je64h1v896048868za200zd896048868&_p=1776804586758&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&are=1&cid=671720968.1776804587&frm=0&pscdl=noapi&rcb=19&sr=800x600&uaa=x86&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115938465~115938469~117266400~117512542~118463261&sid=1776804587&sct=1&seg=0&dl=https%3A%2F%2Filya.grigorik.com%2F&dt=Ilya%20Grigorik&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=1029 — 204 — 550 B — 64 ms — h2https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/size/w256h256/format/png/2022/06/icon-1.svgstorage.ghost.io/c/d1/ab/d1ab7f97-6... https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/size/w256h256/format/png/2022/06/icon-1.svg — 200 — 5.7 KiB — 4 ms — h3https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/2023/01/good-decision-making-is-good-process-final.jpgstorage.ghost.io/c/d1/ab/d1ab7f97-6... https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/2023/01/good-decision-making-is-good-process-final.jpg — 200 — 169.6 KiB — 7 ms — h3https://ilya.grigorik.com/.ghost/analytics/api/v1/page_hit?name=analytics_eventsilya.grigorik.com/.ghost/analytics/... https://ilya.grigorik.com/.ghost/analytics/api/v1/page_hit?name=analytics_events — 202 — 325 B — 149 ms — h2https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/2023/08/Ilya-Grigorik-Guide-to-effective-Meetings.pngstorage.ghost.io/c/d1/ab/d1ab7f97-6... https://storage.ghost.io/c/d1/ab/d1ab7f97-66a2-4047-a903-af92b763a683/content/images/2023/08/Ilya-Grigorik-Guide-to-effective-Meetings.png — 200 — 342.3 KiB — 12 ms — h3
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 390ms · 669KB · $1/mo
jsDelivr
CDN
Optional
Execution 139ms
Transfer 436 KB
Unused 23%
Monthly Cost $0/mo
ilya.grigorik.com
Other
Optional
Execution 81ms
Transfer 19 KB
Monthly Cost $0/mo
Unattributable
Other
Optional
Execution 57ms
Transfer 0 KB
Monthly Cost $0/mo
Google Tag Manager
Tag Manager
Optional
Execution 57ms
Transfer 155 KB
Unused 43%
Monthly Cost $0/mo
ilya.grigorik.com
Other
Optional
Execution 56ms
Transfer 58 KB
Unused 49%
Monthly Cost $0/mo

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

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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