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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
85
GRADE
B
FIX
1
REVIEW
5
PASS
8
INFO
3

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

Mobile Desktop
32
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
93
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
81
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.

3.50 s

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

9.00 s

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

2.80 s

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

0.000

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

7.33 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.

12.94 s

Page Load Progression

564 ms
1.1 s
1.7 s
2.3 s
2.8 s
3.4 s
3.9 s
4.5 s
Checks
17
8 PASS 5 REVIEW 1 FIX
F
JS Execution Cost
Action
15450ms total JS execution
FIX
15450ms total JS execution
Warning::
https://www.blogseo.io/_next/static/chunks/41581ac...: 5191ms CPU time
Warning::
https://www.blogseo.io/: 2689ms CPU time
Warning::
https://www.blogseo.io/_next/static/chunks/3d74d3f...: 2243ms CPU time
Warning::
https://www.blogseo.io/_next/static/chunks/cfcd4a4...: 2115ms CPU time
Warning::
https://www.blogseo.io/ingest/static/posthog-recor...: 1134ms CPU time
Info::
Third-party scripts: 1518ms (10% of total)

Main Thread Breakdown

Script Evaluation 42% Other 35% Style & Layout 14% Rendering 6%
ScriptTotalScriptingParse/CompileParty
https://www.blogseo.io/_next/static/chunks/41581acc9ff71379.js5191ms496ms10ms1st
https://www.blogseo.io/2689ms33ms63ms1st
https://www.blogseo.io/_next/static/chunks/3d74d3f13ce08e0e.js2243ms2222ms17ms1st
https://www.blogseo.io/_next/static/chunks/cfcd4a4cc323de47.js2115ms1647ms21ms1st
https://www.blogseo.io/ingest/static/posthog-recorder.js?v=1.240.61134ms1005ms26ms1st
Unattributable698ms49ms0ms3rd
https://www.blogseo.io/_next/static/chunks/4ffe3e9463762ba4.js402ms209ms37ms1st
https://www.googletagmanager.com/gtag/js?id=G-ZEZN1MWBKJ391ms296ms53ms3rd
https://connect.facebook.net/en_US/fbevents.js157ms119ms36ms3rd
https://connect.facebook.net/signals/config/24303943959281236?v=2.9.291&r=stable&domain=www.blogseo.io&hme=295b1b33901e14aeab879c0b58f907ef4d5f44fdd19814310771af911c5f6ac8&ex_m=102%2C198%2C147%2C22%2C70%2C71%2C139%2C66%2C65%2C11%2C155%2C88%2C16%2C132%2C124%2C37%2C73%2C76%2C130%2C152%2C157%2C8%2C4%2C5%2C7%2C6%2C3%2C89%2C99%2C158%2C163%2C212%2C60%2C179%2C180%2C53%2C267%2C30%2C72%2C224%2C223%2C222%2C23%2C32%2C101%2C59%2C10%2C61%2C95%2C96%2C97%2C103%2C127%2C31%2C29%2C129%2C126%2C125%2C148%2C74%2C151%2C149%2C150%2C48%2C58%2C120%2C15%2C154%2C43%2C254%2C255%2C253%2C26%2C27%2C28%2C46%2C140%2C75%2C110%2C18%2C20%2C42%2C38%2C40%2C39%2C81%2C90%2C94%2C108%2C138%2C141%2C44%2C109%2C24%2C21%2C116%2C67%2C35%2C143%2C142%2C144%2C135%2C133%2C25%2C34%2C57%2C107%2C153%2C68%2C17%2C145%2C112%2C79%2C64%2C19%2C83%2C84%2C113%2C82%2C33%2C284%2C205%2C194%2C195%2C193%2C287%2C279%2C50%2C206%2C105%2C128%2C78%2C118%2C52%2C45%2C47%2C111%2C117%2C123%2C56%2C62%2C51%2C54%2C98%2C156%2C1%2C121%2C14%2C119%2C12%2C2%2C55%2C91%2C63%2C115%2C87%2C86%2C159%2C160%2C92%2C93%2C9%2C122%2C100%2C49%2C136%2C85%2C77%2C69%2C114%2C104%2C41%2C137%2C0%2C80%2C131%2C134%2C146%2C36%2C106%2C13%2C161132ms117ms15ms3rd

Showing top 10 of 14 scripts

B
Page Weight Budget
1.2 MB transferred, 68 requests
REVIEW
1.2 MB transferred, 68 requests
Info::
Page weighs 3.9 MB (1.2 MB transferred)
Warning::
JavaScript is 917 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 917 KB
Info::
68 HTTP requests
Info::
Estimated 0.24 g CO2 per page load
1.2 MB / 2.4 MB budget
1.2 MB transferred
68 requests
0.24 g CO2 per page load
JavaScript 917.4 KiB 78%
Images 107.6 KiB 9%
HTML 62.2 KiB 5%
Other 36.1 KiB 3%
Fonts 30.2 KiB 3%
CSS 20.7 KiB 2%
Other 4.4 KiB 0%
Other 726 B 0%
Other 138 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Under budget

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

B
Image Optimization
21 images, 0 KB saveable
REVIEW
21 images, 0 KB saveable
Info::
All images are well-optimized
21 images 108 KB
0 oversized -0 KB
14 legacy format
0 missing dimensions CLS risk
C
JS Bundles
Action
29 scripts, 284 KB unused
REVIEW
29 scripts, 284 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-ZEZN...: 70 KB unused (41%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.blogseo.io/ingest/static/posthog-recor...: 62 KB unused (70%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://connect.facebook.net/en_US/fbevents.js: 34 KB unused (36%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.blogseo.io/_next/static/chunks/4ffe3e9...: 25 KB unused (21%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.blogseo.io/ingest/static/surveys.js?v=...: 25 KB unused (78%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 284 KB
284 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-ZEZN1MWBKJ172 KB70 KB (41%)✓3rd
https://www.blogseo.io/ingest/static/posthog-recorder.js?v=1.240.688 KB62 KB (70%)✓1st
https://connect.facebook.net/en_US/fbevents.js95 KB34 KB (36%)✓3rd
https://www.blogseo.io/_next/static/chunks/4ffe3e9463762ba4.js121 KB25 KB (21%)✓1st
https://www.blogseo.io/ingest/static/surveys.js?v=1.240.632 KB25 KB (78%)✓1st
https://www.blogseo.io/_next/static/chunks/cfcd4a4cc323de47.js67 KB25 KB (37%)✓1st
https://www.blogseo.io/_next/static/chunks/d5b43125594664c9.js39 KB22 KB (58%)✓1st
https://www.blogseo.io/_next/static/chunks/3d74d3f13ce08e0e.js59 KB21 KB (36%)✓1st
https://www.blogseo.io/_next/static/chunks/ff1a16fafef87110.js0 KB—✓1st
https://www.blogseo.io/_next/static/chunks/turbopack-450609e072091725.js4 KB—✓1st

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

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

B
HTTP Caching
public, max-age=0, must-revalidate
REVIEW
public, max-age=0, must-revalidate
Info::
Cache-Control header is set
Got: public, max-age=0, must-revalidate
Info::
ETag present — enables conditional (304) responses
Cache-Control

public, max-age=0, must-revalidate

DirectiveValueMeaning
public—Any cache may store this response
max-age0Cache for 0 seconds
must-revalidate—Must recheck with server after expiry
A
Third-Party Impact
37% third-party, 0 ms blocking
PASS
37% third-party, 0 ms blocking
Info::
Third-party code accounts for 37% of page weight (441.6 KiB of 1.2 MiB)
Info::
Third-party blocking time is low (0 ms)
63%
37%
First-party Third-party
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+
Font Loading
2 fonts (30 KB)
PASS
2 fonts (30 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

30 KB total

Render-blocking

0

of 2

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 8.0 s 9.0 s FCP 3.5 s LCP 9.0 shttps://www.blogseo.io/_next/static/media/400bf8aa837fcb7e-s.p.b68677ba.woff2400bf8aa837fcb7e-s.p.b6... https://www.blogseo.io/_next/static/media/400bf8aa837fcb7e-s.p.b68677ba.woff2 — 10.2 KiB — 0 ms — font-display: swaphttps://www.blogseo.io/_next/static/media/f7aa21714c1c53f8-s.p.e3544bb0.woff2f7aa21714c1c53f8-s.p.e3... https://www.blogseo.io/_next/static/media/f7aa21714c1c53f8-s.p.e3544bb0.woff2 — 19.9 KiB — 0 ms — font-display: swap
400bf8aa837fcb7e-s.p.b6... woff2 swap
Size 10 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
f7aa21714c1c53f8-s.p.e3... woff2 swap
Size 20 KB
Load time 0 ms
Start 0 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
19 hints, 0 missing preconnects
PASS
19 hints, 0 missing preconnects
Info::
Page uses 19 resource hint(s)

Current Resource Hints

preconnect
—
preload
+9
19
dns-prefetch
—
prefetch
—

19 resource hints configured

A+
Render-Blocking Resources
No render-blocking resources detected
PASS
No render-blocking resources detected
Info::
No render-blocking resources detected in <head>
A+
Third-Party Resources
No third-party resources detected
PASS
No third-party resources detected
Network Waterfall
68 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
10% of JavaScript execution is third-party
First-party Third-party 1518ms · 313KB · €24/mo
Unattributable
Other
Costly
Execution 698ms
Transfer 0 KB
Monthly Cost €11/mo
Google Tag Manager
Tag Manager
Costly
Execution 391ms
Transfer 172 KB
Unused 41%
Monthly Cost €6/mo
Facebook Pixel
Advertising
Optional
Execution 157ms
Transfer 95 KB
Unused 36%
Monthly Cost €3/mo
Facebook Pixel
Advertising
Optional
Execution 132ms
Transfer 37 KB
Monthly Cost €2/mo
datafa.st
Other
Optional
Execution 81ms
Transfer 5 KB
Monthly Cost €1/mo
cdn.affonso.io
Other
Optional
Execution 59ms
Transfer 3 KB
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • Unattributable adds 698ms and costs ~€11/month
  • Google Tag Manager adds 391ms and costs ~€6/month

Unattributable takes 698ms 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 391ms 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

Real-User Performance (CrUX)
Field metrics from the Chrome User Experience Report
INFO

Chrome User Experience (CrUX)

Real-user metrics from the Chrome UX Report (2026-03-08 — 2026-04-04)

LCP (p75)

1975 ms

84% good

INP (p75)

133 ms

85% good

CLS (p75)

0.000

98% good

FCP (p75)

1991 ms

TTFB (p75)

836 ms

This origin passes Core Web Vitals assessment
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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