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Performance

· 26 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
94
GRADE
A
FIX
0
REVIEW
6
PASS
17
INFO
3

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

Mobile Desktop
72
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
96
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.

3.22 s

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

4.96 s

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

86 ms

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.

5.17 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.

4.96 s

Page Load Progression

402 ms
804 ms
1.2 s
1.6 s
2.0 s
2.4 s
2.8 s
3.2 s
Checks
26
17 PASS 6 REVIEW
B
JS Bundles
1 scripts, 65 KB unused
REVIEW
1 scripts, 65 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-PLBH...: 65 KB unused (41%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 65 KB
65 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-PLBHMZT9E5157 KB65 KB (41%)✓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

B
HTTP/3 (QUIC)
HTTP/3 not advertised
REVIEW
HTTP/3 not advertised
Info::
HTTP/3 (QUIC) is not advertised
HTTP/3 isn't advertised via Alt-Svc and the worker didn't negotiate h3. HTTP/3 reduces handshake latency (1-RTT instead of 2-3 RTTs) and is more resilient on lossy connections. Most modern CDNs (Cloudflare, Fastly, AWS CloudFront, Google Cloud CDN) support HTTP/3 with a single config switch -- consider enabling for mobile-heavy workloads.
C
Compression Algorithm
Action
Main response served uncompressed
REVIEW
Main response served uncompressed
Info::
Main HTML response has no Content-Encoding (uncompressed)
The main HTML document is served without compression. The Text Compression section above lists the broader picture; for the main response specifically, even gzip would shave ~70-80% off most text payloads.
B
Server-Timing Observability
No Server-Timing header found
REVIEW
No Server-Timing header found
Info::
No Server-Timing header found
Server-Timing exposes backend timing breakdowns to browser DevTools (e.g., `db: 45ms; render: 120ms; cache: 2ms`). Useful for diagnosing slow pages without backend log access. Most modern frameworks (Next.js, Cloudflare Workers, Fastly) emit it automatically; absence on a managed platform usually means telemetry headers are stripped at the edge.
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+
Page Weight Budget
616 KB transferred, 8 requests
PASS
616 KB transferred, 8 requests
Info::
Page weighs 1.1 MB (616 KB transferred)
Info::
8 HTTP requests
Info::
Estimated 0.13 g CO2 per page load
616 KB / 2.4 MB budget
616 KB transferred
8 requests
0.13 g CO2 per page load
Images 311.5 KiB 51%
JavaScript 157.2 KiB 25%
Fonts 140.0 KiB 23%
CSS 3.0 KiB 0%
HTML 2.6 KiB 0%
Other 1.6 KiB 0%
Other 547 B 0%
0 2.4 MB 4.9 MB
Under budget
A
Third-Party Impact
26% third-party, 0 ms blocking
PASS
26% third-party, 0 ms blocking
Info::
Third-party code accounts for 26% of page weight (157.7 KiB of 616.5 KiB)
Info::
Third-party blocking time is low (0 ms)
74%
26%
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
Image Optimization
1 images, 0 KB saveable
PASS
1 images, 0 KB saveable
Warning::
https://hannahseo.com/assets/images/hannah-seo.jpg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
1 images 312 KB
0 oversized -0 KB
1 legacy format
1 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

A+
JS Execution Cost
405ms total JS execution
PASS
405ms total JS execution
Info::
https://hannahseo.com/: 171ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-PLBH...: 130ms CPU time
Info::
Unattributable: 104ms CPU time
Warning::
Third-party scripts: 234ms (58% of total)

Main Thread Breakdown

Script Evaluation 48% Other 33% Style & Layout 9% Script Parsing & Compilation 8%
ScriptTotalScriptingParse/CompileParty
https://hannahseo.com/171ms101ms1ms1st
https://www.googletagmanager.com/gtag/js?id=G-PLBHMZT9E5130ms87ms32ms3rd
Unattributable104ms5ms0ms3rd
A+
Font Loading
2 fonts (140 KB)
PASS
2 fonts (140 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

140 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 FCP 3.2 s LCP 5.0 shttps://hannahseo.com/assets/fonts/dosis.ttfdosis.ttf https://hannahseo.com/assets/fonts/dosis.ttf — 55.5 KiB — 225 ms — font-display: swaphttps://hannahseo.com/assets/fonts/playfair-display-medium.ttfplayfair-display-medium... https://hannahseo.com/assets/fonts/playfair-display-medium.ttf — 84.5 KiB — 490 ms — font-display: swap
dosis.ttf ttf swap
Size 56 KB
Load time 225 ms
Start 571 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
playfair-display-medium... ttf swap
Size 84 KB
Load time 490 ms
Start 571 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
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 ~42 KB and ~84 ms

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
A+
LCP Image Preload
LCP preload audit not available
PASS
LCP preload audit not available
Info::
LCP image preload audit not available for this scan
A+
Main HTML Cache-Control
Main HTML max-age=0 (≤ 5min) is appropriate
PASS
Main HTML max-age=0 (≤ 5min) is appropriate
Info::
Main HTML max-age=0 (≤ 5min) is appropriate
Got: public,max-age=0,must-revalidate
A+
Server Response Intelligence
3 server-response signal(s) detected
PASS
3 server-response signal(s) detected
Info::
`Cache-Status` header present (RFC 9211): "Netlify Edge"; fwd=miss
The page returns a `Cache-Status` header -- the standardized way for CDNs and caches to communicate per-hop cache state to debugging tools. Format: `Cache-Status: cdn-name; hit; ttl=300` (or `; fwd=miss` / `; fwd=stale`). Standard alternative to vendor-specific `X-Cache` patterns each CDN had historically. Cloudflare, Fastly, and Akamai all support emitting it.
Info::
`Vary` header declared: Accept-Encoding
The page declares a `Vary` header, telling downstream caches which request headers the response varies on. Critical for content-negotiated responses (compression, language, cookies, device class).
Info::
`ETag` present -- conditional GET supported
A+
Page Weight Inventory
8 resources · 616 KB · 65 KB savings available
PASS
8 resources · 616 KB · 65 KB savings available
Info::
Within 1MB page-weight target
Got: 616 KB
Info::
~65 KB of savings available
Info::
2 third-party resources (26% of weight)
Info::
1 resources over 200KB
8 resources · 616.5 KiB · 2 third-party Within 1MB page-weight target
Image 51% · 311.5 KiB
JavaScript 25% · 157.2 KiB
Font 23% · 140.0 KiB
Document 1% · 4.2 KiB
CSS 0% · 3.0 KiB
Other 0% · 547 B

~64.8 KiB of savings available

Remove unused JavaScript: 64.8 KiB
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
A+
JavaScript Blocking
No render-blocking JS or document.write usage detected
PASS
No render-blocking JS or document.write usage detected
Info::
No JavaScript blocking issues detected
A+
CSS Performance Depth
No CSS performance depth issues detected
PASS
No CSS performance depth issues detected
Info::
No CSS performance depth issues detected
Network Waterfall
8 requests over 1220ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s FCP 3.2 s LCP 5.0 shttps://hannahseo.com// https://hannahseo.com/ — 200 — 2.6 KiB — 224 ms — h2https://hannahseo.com/assets/main.css/assets/main.css https://hannahseo.com/assets/main.css — 200 — 3.0 KiB — 286 ms — h2https://www.googletagmanager.com/gtag/js?id=G-PLBHMZT9E5www.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-PLBHMZT9E5 — 200 — 157.2 KiB — 267 ms — h2https://hannahseo.com/assets/images/hannah-seo.jpg/assets/images/hannah-seo.jpg https://hannahseo.com/assets/images/hannah-seo.jpg — 200 — 311.5 KiB — 285 ms — h2https://region1.google-analytics.com/g/collect?v=2&tid=G-PLBHMZT9E5&gtm=45je6562v9188459471za200zd9188459471&_p=1778416941077&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&are=1&cid=845798622.1778416941&frm=0&pscdl=noapi&rcb=15&sr=412x823&uaa=&uab=64&uafvl=Not%252FA)Brand%3B99.0.0.0%7CChromium%3B148.0.7778.96&uam=moto%20g%20power%20(2022)&uamb=1&uap=Android&uapv=11.0&uaw=0&ul=en-us&_s=1&tag_exp=0~115938465~115938468~118463262&sid=1778416941&sct=1&seg=0&dl=https%3A%2F%2Fhannahseo.com%2F&dt=Hannah%20Seo%20%7C%20Hannah%20Seo%20is%20a%20Korean-Canadian%20freelance%20journalist%2C%20writer%2C%20and%20fact-checker%20covering%20science%2C%20health%2C%20and%20culture%20for%20The%20Atlantic%2C%20Vox%2C%20The%20Guardian%2C%20NYT%20Magazine%2C%20and%20more.&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=560region1.google-analytics.com/g/coll... https://region1.google-analytics.com/g/collect?v=2&tid=G-PLBHMZT9E5&gtm=45je6562v9188459471za200zd9188459471&_p=1778416941077&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&are=1&cid=845798622.1778416941&frm=0&pscdl=noapi&rcb=15&sr=412x823&uaa=&uab=64&uafvl=Not%252FA)Brand%3B99.0.0.0%7CChromium%3B148.0.7778.96&uam=moto%20g%20power%20(2022)&uamb=1&uap=Android&uapv=11.0&uaw=0&ul=en-us&_s=1&tag_exp=0~115938465~115938468~118463262&sid=1778416941&sct=1&seg=0&dl=https%3A%2F%2Fhannahseo.com%2F&dt=Hannah%20Seo%20%7C%20Hannah%20Seo%20is%20a%20Korean-Canadian%20freelance%20journalist%2C%20writer%2C%20and%20fact-checker%20covering%20science%2C%20health%2C%20and%20culture%20for%20The%20Atlantic%2C%20Vox%2C%20The%20Guardian%2C%20NYT%20Magazine%2C%20and%20more.&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=560 — 204 — 547 B — 90 ms — h2https://hannahseo.com/assets/fonts/dosis.ttf/assets/fonts/dosis.ttf https://hannahseo.com/assets/fonts/dosis.ttf — 200 — 55.5 KiB — 225 ms — h2https://hannahseo.com/assets/fonts/playfair-display-medium.ttf/assets/fonts/playfair-display-medi... https://hannahseo.com/assets/fonts/playfair-display-medium.ttf — 200 — 84.5 KiB — 490 ms — h2https://hannahseo.com/favicon.ico/favicon.ico https://hannahseo.com/favicon.ico — 404 — 1.6 KiB — 149 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
58% of JavaScript execution is third-party
First-party Third-party 234ms · 157KB · $1/mo
Google Tag Manager
Tag Manager
Optional
Execution 130ms
Transfer 157 KB
Unused 41%
Monthly Cost $0/mo
Unattributable
Other
Optional
Execution 104ms
Transfer 0 KB
Monthly Cost $0/mo

58% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

Learn more ▾

Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

How third-party costs are calculated

Image Optimization
1 images, 311 KB total, 266 KB wasted
INFO

Image Optimization Audit

Total Images

1

Total Size

311 KB

Oversized

1

Wasted

266 KB

1 missing dimensions 1 missing lazy loading
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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