Performance

· 27 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

100

Accessibility

100

Best Practices

SEO

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

2.38 s

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

2.72 s

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

332 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.

4.87 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.

7.84 s

Page Load Progression

389 ms

779 ms

1.2 s

1.6 s

1.9 s

2.3 s

2.7 s

3.1 s

Checks

14 PASS 7 REVIEW 2 FIX

JS Execution Cost

Action

8259ms total JS execution

FIX

8259ms total JS execution

https://localxlist.org/_next/static/chunks/961311c...: 6679ms CPU time

Unattributable: 679ms CPU time

https://localxlist.org/: 499ms CPU time

https://www.googletagmanager.com/gtag/js?id=G-KEWL...: 323ms CPU time

https://localxlist.org/_next/static/chunks/67c9d06...: 80ms CPU time

Third-party scripts: 323ms (4% of total)

Main Thread Breakdown

Script Evaluation 67% Other 25%

Script	Total	Scripting	Parse/Compile	Party
https://localxlist.org/_next/static/chunks/961311cbebbffb6d.js	6679ms	5194ms	24ms	1st
Unattributable	679ms	24ms	0ms	1st
https://localxlist.org/	499ms	30ms	16ms	1st
https://www.googletagmanager.com/gtag/js?id=G-KEWLXSC3R0	323ms	272ms	47ms	3rd
https://localxlist.org/_next/static/chunks/67c9d06fa8700707.js	80ms	50ms	19ms	1st

HTTP Caching

Action

no-store (uncacheable)

FIX

no-store (uncacheable)

Cache-Control: no-store prevents all caching

Intentional for dynamic content, but increases server load for every page view.

Got: private, no-cache, no-store, max-age=0, must-revalidate

No ETag or Last-Modified header

Conditional requests (304 Not Modified) are not possible without validators.

Cache-Control

private, no-cache, no-store, max-age=0, must-revalidate

Directive	Value	Meaning
private	—	Only browser cache, not CDN/proxy
no-cache	—	Cache but always revalidate first
no-store	—	Never cache this response
max-age	0	Cache for 0 seconds
must-revalidate	—	Must recheck with server after expiry

JS Bundles

19 scripts, 96 KB unused

REVIEW

19 scripts, 96 KB unused

https://www.googletagmanager.com/gtag/js?id=G-KEWL...: 70 KB unused (42%)

Consider code splitting or tree shaking to reduce unused code.

https://localxlist.org/_next/static/chunks/961311c...: 25 KB unused (31%)

Consider code splitting or tree shaking to reduce unused code.

Total unused JavaScript: 96 KB

96 KB unused JavaScript

Downloaded but never executed on this page.

Script	Size	Unused	Minified	Party
https://www.googletagmanager.com/gtag/js?id=G-KEWLXSC3R0	166 KB	70 KB (42%)	✓	3rd
https://localxlist.org/_next/static/chunks/961311cbebbffb6d.js	81 KB	25 KB (31%)	✓	1st
https://localxlist.org/_next/static/chunks/4b188ae602b9c4db.js	21 KB	—	✓	1st
https://localxlist.org/_next/static/chunks/744634c9afe0570c.js	22 KB	—	✓	1st
https://localxlist.org/_next/static/chunks/ede8a4b7a28a7a18.js	10 KB	—	✓	1st
https://localxlist.org/_next/static/chunks/797fcb0710da3be2.js	8 KB	—	✓	1st
https://localxlist.org/_next/static/chunks/turbopack-0f2881c0c5767128.js	5 KB	—	✓	1st
https://localxlist.org/_next/static/chunks/f249787193ec3d93.js	5 KB	—	✓	1st
https://localxlist.org/_next/static/chunks/102a67e358ac219f.js	2 KB	—	✓	1st
https://localxlist.org/_next/static/chunks/f7aec44ebff1872f.js	10 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

Resource Hints

7 hints, 0 missing preconnects

REVIEW

7 hints, 0 missing preconnects

3 font preload(s) missing `crossorigin` -- font will be downloaded twice

Fonts are always fetched as crossorigin=anonymous; a preload without the attribute creates a different cache key, so the browser refetches when the actual font request happens. Sample: /_next/static/media/1bc7fc94203521e3-s.p.888a2ca8.woff2, /_next/static/media/216579b50e548914-s.p.a1b609f7.woff2, /_next/static/media/3df2de83712245dd-s.p.b86f99c9.woff2. Add `crossorigin` (or `crossorigin="anonymous"`) to each preload.

1 dns-prefetch redundant with preconnect on same origin

preconnect already does the DNS lookup; adding dns-prefetch to the same origin is at best a no-op. Sample: https://api.localxlist.net. Remove the redundant dns-prefetch entries.

Page uses 7 resource hint(s)

Current Resource Hints

preconnect

preload

dns-prefetch

prefetch

—

7 resource hints configured

Why this matters

Performance issues directly impact user engagement and conversion rates.

preconnect already does the DNS lookup; adding dns-prefetch to the same origin is at best a no-op. Sample: https://api.localxlist.net. Remove the redundant dns-prefetch entries.

Why this matters

Performance issues directly impact user engagement and conversion rates.

HTTP/3 (QUIC)

HTTP/3 not advertised

REVIEW

HTTP/3 not advertised

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.

Compression Algorithm

Main response uses gzip; brotli would be ~20% smaller

REVIEW

Main response uses gzip; brotli would be ~20% smaller

Main HTML response uses gzip (brotli would be ~20% smaller)

All current browsers support brotli. Most CDNs (Cloudflare, Fastly, AWS CloudFront, Vercel, Netlify) can switch from gzip to brotli with a single config flag. Origin servers (nginx, Apache) need a brotli module compiled in -- nginx-brotli or Apache mod_brotli.

Server-Timing Observability

No Server-Timing header found

REVIEW

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.

JavaScript Blocking

2 JS blocking issue(s) detected

REVIEW

2 JS blocking issue(s) detected

1 render-blocking <script src> tag(s) without async/defer

Each `<script src=...>` without `async`, `defer`, or `type="module"` blocks HTML parsing while the browser fetches and executes it. The block lasts the entire round-trip + execution time -- on slow networks this translates directly into LCP delay. Add `defer` (executes after parse, in source order) for scripts that interact with the DOM, or `async` (executes whenever ready) for analytics / independent scripts. Module scripts (`type="module"`) are deferred by default.

Total JS execution time is 8.3 s -- over the 3.5s budget

Total JavaScript execution (parse + compile + run) across all scripts exceeds 3.5 seconds. On low-end devices that becomes 7-15+ seconds and shows up directly in TBT and INP. Reduce by: tree-shaking unused dependencies, code-splitting (dynamic `import()`), removing or deferring third-party tracking, and replacing heavy frameworks where they're not needed.

Green Hosting

Action

Whether the site is served from green-energy infrastructure

REVIEW

Green Hosting

No green hosting detected

A+

Page Weight Budget

557 KB transferred, 61 requests

PASS

557 KB transferred, 61 requests

Page weighs 1.7 MB (557 KB transferred)

61 HTTP requests

Estimated 0.11 g CO2 per page load

557 KB transferred

61 requests

0.11 g CO2 per page load

JavaScript 402.5 KiB 72%

HTML 45.6 KiB 8%

Fonts 43.3 KiB 8%

CSS 31.7 KiB 6%

Images 26.4 KiB 5%

Other 5.2 KiB 1%

Other 1.9 KiB 0%

Other 557 B 0%

Other 0 B 0%

0 2.4 MB 4.9 MB

Under budget

Third-Party Impact

31% third-party, 0 ms blocking

PASS

31% third-party, 0 ms blocking

Third-party code accounts for 31% of page weight (170.2 KiB of 557.2 KiB)

Third-party blocking time is low (0 ms)

69%

31%

First-party Third-party

A+

Text Compression

All text resources are compressed

PASS

All text resources are compressed

All text resources are properly compressed.

A+

Image Optimization

27 images, 0 KB saveable

PASS

27 images, 0 KB saveable

All images are well-optimized

27 images 26 KB

0 oversized -0 KB

1 legacy format

0 missing dimensions CLS risk

A+

Font Loading

3 fonts (43 KB)

PASS

3 fonts (43 KB)

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

Web fonts

43 KB total

Render-blocking

of 3

Dominant font-display

swap

Most common across fonts

Font loading timeline

Transfer FOIT (block) FOUT (swap)

1bc7fc94203521e3-s.p.88... woff2 swap

Size 15 KB

Load time 881 ms

Start 1.1 s

Risk FOUT — text flashes from fallback to web font

216579b50e548914-s.p.a1... woff2 swap

Size 14 KB

Load time 1.4 s

Start 1.1 s

Risk FOUT — text flashes from fallback to web font

3df2de83712245dd-s.p.b8... woff2 swap

Size 14 KB

Load time 1.5 s

Start 1.1 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)

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+

LCP Image Preload

LCP preload audit not available

PASS

LCP preload audit not available

LCP image preload audit not available for this scan

A+

Main HTML Cache-Control

Main HTML uses no-store -- correct for sensitive/dynamic content

PASS

Main HTML uses no-store -- correct for sensitive/dynamic content

Got: private, no-cache, no-store, max-age=0, must-revalidate

A+

Server Response Intelligence

2 server-response signal(s) detected

PASS

2 server-response signal(s) detected

`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).

No `ETag` or `Last-Modified` -- conditional GET not supported

Without either header, browsers can't issue conditional GETs and refresh always re-downloads the full response body even when nothing changed. Add `ETag: "<hash>"` (or `Last-Modified: <date>`) on cacheable responses; the server returns 304 Not Modified when the client's cached copy is still valid, saving bandwidth.

A+

Page Weight Inventory

61 resources · 557 KB · 96 KB savings available

PASS

61 resources · 557 KB · 96 KB savings available

Within 1MB page-weight target

Got: 557 KB

~96 KB of savings available

7 third-party resources (31% of weight)

61 resources · 557.2 KiB · 7 third-party Within 1MB page-weight target

JavaScript 72% · 402.5 KiB

Document 8% · 45.6 KiB

Font 8% · 43.3 KiB

CSS 6% · 31.7 KiB

Image 5% · 28.3 KiB

Other 1% · 5.7 KiB

~95.6 KiB of savings available

Remove unused JavaScript: 95.6 KiB

#	Resource	Type	Size	Cache	Unused	3rd party	Issues

61 resources			557.2 KiB

A+

Render-Blocking Resources

No render-blocking resources detected

PASS

No render-blocking resources detected

No render-blocking resources detected in <head>

A+

Third-Party Resources

No third-party resources detected

PASS

No third-party resources detected

A+

CSS Performance Depth

No CSS performance depth issues detected

PASS

No CSS performance depth issues detected

Network Waterfall

61 requests over 6533ms

INFO

HTML JavaScript CSS Images Fonts XHR/Fetch Other

Third-Party Script Cost

Per-script blocking time, transfer cost, and cache headers

INFO

4% of JavaScript execution is third-party

First-party Third-party 323ms · 166KB · $4/mo

Script	Category	Execution	Transfer	Unused	Monthly Cost	Verdict
Google Tag Manager www.googletagmanager.com	Tag Manager	323ms	166 KB	42%	$4/mo	Costly

Google Tag Manager

Tag Manager

Costly

Execution 323ms

Transfer 166 KB

Unused 42%

Monthly Cost $4/mo

These scripts may cost more than they're worth

Google Tag Manager adds 323ms and costs ~$4/month

Google Tag Manager takes 323ms 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 (2026-07-20 — 2026-08-16)

LCP (p75)

2976 ms

67% good

INP (p75)

136 ms

86% good

CLS (p75)

0.010

95% good

FCP (p75)

2965 ms

TTFB (p75)

1694 ms

Image Optimization

26 images, 9 KB total, 0 KB wasted

INFO

Image Optimization Audit

Total Images

Total Size

9 KB

15 missing lazy loading

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.