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Performance

· 25 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
96
GRADE
A
FIX
2
REVIEW
0
PASS
21
INFO
2

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

Mobile Desktop
62
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
90
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
100
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
91
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.

3.75 s

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

7.06 s

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

208 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.

5.22 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.

7.45 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
25
21 PASS 2 FIX
D
JS Execution Cost
Action
2247ms total JS execution
FIX
2247ms total JS execution
Warning::
https://costdown.org/: 857ms CPU time
Warning::
https://costdown.org/_next/static/chunks/1255-fc6c...: 666ms CPU time
Warning::
Unattributable: 353ms CPU time
Info::
https://costdown.org/_next/static/chunks/4bd1b696-...: 241ms CPU time
Info::
https://costdown.org/_next/static/chunks/8009-265e...: 131ms CPU time

Main Thread Breakdown

Script Evaluation 39% Style & Layout 29% Other 20% Script Parsing & Compilation 7%
ScriptTotalScriptingParse/CompileParty
https://costdown.org/857ms46ms16ms1st
https://costdown.org/_next/static/chunks/1255-fc6c00ab2f765339.js666ms523ms45ms1st
Unattributable353ms27ms0ms1st
https://costdown.org/_next/static/chunks/4bd1b696-f785427dddbba9fb.js241ms215ms25ms1st
https://costdown.org/_next/static/chunks/8009-265e6cb796d00673.js131ms61ms70ms1st
D
HTTP Caching
Action
no-store (uncacheable)
FIX
no-store (uncacheable)
Info::
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
Info::
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

DirectiveValueMeaning
private—Only browser cache, not CDN/proxy
no-cache—Cache but always revalidate first
no-store—Never cache this response
max-age0Cache for 0 seconds
must-revalidate—Must recheck with server after expiry
A+
Page Weight Budget
568 KB transferred, 25 requests
PASS
568 KB transferred, 25 requests
Info::
Page weighs 1.4 MB (568 KB transferred)
Info::
Fonts are 217 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 217 KB
Info::
25 HTTP requests
Info::
Estimated 0.12 g CO2 per page load
568 KB / 2.4 MB budget
568 KB transferred
25 requests
0.12 g CO2 per page load
JavaScript 299.4 KiB 53%
Fonts 216.7 KiB 38%
HTML 14.3 KiB 3%
Other 14.0 KiB 2%
Images 10.5 KiB 2%
CSS 8.7 KiB 2%
Other 3.8 KiB 1%
Other 445 B 0%
0 2.4 MB 4.9 MB
Under budget

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

A+
Third-Party Impact
2% third-party, 0 ms blocking
PASS
2% third-party, 0 ms blocking
Info::
Third-party code accounts for 2% of page weight (11.3 KiB of 568.0 KiB)
Info::
Third-party blocking time is low (0 ms)
98%
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
Info::
All images are well-optimized
1 images 10 KB
0 oversized -0 KB
1 legacy format
0 missing dimensions CLS risk
A+
Font Loading
6 fonts (217 KB)
PASS
6 fonts (217 KB)
Info::
6 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

6

217 KB total

Render-blocking

0

of 6

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 FCP 3.7 s LCP 7.1 shttps://costdown.org/_next/static/media/62c97acc3aa63787-s.p.woff262c97acc3aa63787-s.p.woff2 https://costdown.org/_next/static/media/62c97acc3aa63787-s.p.woff2 — 12.8 KiB — 854 ms — font-display: swaphttps://costdown.org/_next/static/media/8e9860b6e62d6359-s.p.woff28e9860b6e62d6359-s.p.woff2 https://costdown.org/_next/static/media/8e9860b6e62d6359-s.p.woff2 — 84.4 KiB — 1.0 s — font-display: swaphttps://costdown.org/_next/static/media/bb3ef058b751a6ad-s.p.woff2bb3ef058b751a6ad-s.p.woff2 https://costdown.org/_next/static/media/bb3ef058b751a6ad-s.p.woff2 — 40.6 KiB — 1.0 s — font-display: swaphttps://costdown.org/_next/static/media/e4af272ccee01ff0-s.p.woff2e4af272ccee01ff0-s.p.woff2 https://costdown.org/_next/static/media/e4af272ccee01ff0-s.p.woff2 — 48.4 KiB — 1.0 s — font-display: swaphttps://costdown.org/_next/static/media/df0a9ae256c0569c-s.woff2df0a9ae256c0569c-s.woff2 https://costdown.org/_next/static/media/df0a9ae256c0569c-s.woff2 — 11.1 KiB — 828 ms — font-display: swaphttps://costdown.org/_next/static/media/21350d82a1f187e9-s.woff221350d82a1f187e9-s.woff2 https://costdown.org/_next/static/media/21350d82a1f187e9-s.woff2 — 19.4 KiB — 855 ms — font-display: swap
62c97acc3aa63787-s.p.woff2 woff2 swap
Size 13 KB
Load time 854 ms
Start 264 ms
Risk FOUT — text flashes from fallback to web font
8e9860b6e62d6359-s.p.woff2 woff2 swap
Size 84 KB
Load time 1.0 s
Start 264 ms
Risk FOUT — text flashes from fallback to web font
bb3ef058b751a6ad-s.p.woff2 woff2 swap
Size 41 KB
Load time 1.0 s
Start 264 ms
Risk FOUT — text flashes from fallback to web font
e4af272ccee01ff0-s.p.woff2 woff2 swap
Size 48 KB
Load time 1.0 s
Start 265 ms
Risk FOUT — text flashes from fallback to web font
df0a9ae256c0569c-s.woff2 woff2 swap
Size 11 KB
Load time 828 ms
Start 1.2 s
Risk FOUT — text flashes from fallback to web font
21350d82a1f187e9-s.woff2 woff2 swap
Size 19 KB
Load time 855 ms
Start 1.2 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+
JS Bundles
11 scripts, 0 KB unused
PASS
11 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://costdown.org/_next/static/chunks/webpack-acb34275d54b1fbc.js3 KB—✓1st
https://costdown.org/_next/static/chunks/4bd1b696-f785427dddbba9fb.js54 KB—✓1st
https://costdown.org/_next/static/chunks/1255-fc6c00ab2f765339.js47 KB—✓1st
https://costdown.org/_next/static/chunks/main-app-05a5fe279f4f6e20.js1 KB—✓1st
https://costdown.org/_next/static/chunks/2619-3c9e02e22d10480a.js4 KB—✓1st
https://costdown.org/_next/static/chunks/8009-265e6cb796d00673.js148 KB—✓1st
https://costdown.org/_next/static/chunks/2337-d8f99f4e41701169.js4 KB—✓1st
https://costdown.org/_next/static/chunks/app/%5Blang%5D/layout-a1ce92e8d46a0a79.js4 KB—✓1st
https://costdown.org/_next/static/chunks/5905-66bd670be201cd25.js20 KB—✓1st
https://costdown.org/_next/static/chunks/app/%5Blang%5D/page-778be06fec310a48.js2 KB—✓1st
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
5 hints, 0 missing preconnects
PASS
5 hints, 0 missing preconnects
Info::
Page uses 5 resource hint(s)

Current Resource Hints

preconnect
—
preload
5
dns-prefetch
—
prefetch
—

5 resource hints configured

A+
HTTP/3 (QUIC)
HTTP/3 advertised via Alt-Svc
PASS
HTTP/3 advertised via Alt-Svc
Info::
HTTP/3 (QUIC) is supported
First-load mobile users on cellular networks see meaningful latency improvements with HTTP/3. The QUIC transport collapses TLS + TCP handshakes into one and recovers faster from packet loss.
A+
Compression Algorithm
Main response uses brotli
PASS
Main response uses brotli
Info::
Main HTML response uses brotli (Content-Encoding: br)
Brotli is the best text-compression algorithm for general use, ~20% smaller than gzip on average (40% on smaller files). Modern browsers all support it.
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 uses no-store -- correct for sensitive/dynamic content
PASS
Main HTML uses no-store -- correct for sensitive/dynamic content
Info::
Main HTML uses no-store -- correct for sensitive/dynamic content
Got: private, no-cache, no-store, max-age=0, must-revalidate
A+
Server-Timing Observability
3 Server-Timing entries advertised
PASS
3 Server-Timing entries advertised
Info::
Server-Timing header advertises 3 timing entries
A+
Server Response Intelligence
2 server-response signal(s) detected
PASS
2 server-response signal(s) detected
Info::
`Vary` header declared: rsc, next-router-state-tree, next-router-prefetch, next-router-segment-prefetch,...
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::
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
25 resources · 568 KB · 0 KB savings available
PASS
25 resources · 568 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 568 KB
Info::
1 third-party resources (2% of weight)
25 resources · 568.0 KiB · 1 third-party Within 1MB page-weight target
JavaScript 53% · 299.4 KiB
Font 38% · 216.7 KiB
Document 5% · 28.4 KiB
Image 2% · 10.5 KiB
CSS 2% · 8.7 KiB
Other 1% · 4.3 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
1 JS blocking issue(s) detected
PASS
1 JS blocking issue(s) detected
Warning::
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.
A+
CSS Performance Depth
No CSS performance depth issues detected
PASS
No CSS performance depth issues detected
Info::
No CSS performance depth issues detected
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Cloudflare

Network Waterfall
25 requests over 2648ms
INFO
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s 6.0 s 7.0 s FCP 3.7 s LCP 7.1 shttps://costdown.org// https://costdown.org/ — 200 — 14.3 KiB — 413 ms — h3https://costdown.org/_next/static/media/62c97acc3aa63787-s.p.woff2/_next/static/media/62c97acc3aa6378... https://costdown.org/_next/static/media/62c97acc3aa63787-s.p.woff2 — 200 — 12.8 KiB — 854 ms — h3https://costdown.org/_next/static/media/8e9860b6e62d6359-s.p.woff2/_next/static/media/8e9860b6e62d635... https://costdown.org/_next/static/media/8e9860b6e62d6359-s.p.woff2 — 200 — 84.4 KiB — 1.0 s — h3https://costdown.org/_next/static/media/bb3ef058b751a6ad-s.p.woff2/_next/static/media/bb3ef058b751a6a... https://costdown.org/_next/static/media/bb3ef058b751a6ad-s.p.woff2 — 200 — 40.6 KiB — 1.0 s — h3https://costdown.org/_next/static/media/e4af272ccee01ff0-s.p.woff2/_next/static/media/e4af272ccee01ff... https://costdown.org/_next/static/media/e4af272ccee01ff0-s.p.woff2 — 200 — 48.4 KiB — 1.0 s — h3https://costdown.org/_next/static/css/64128db1240a9610.css/_next/static/css/64128db1240a9610.... https://costdown.org/_next/static/css/64128db1240a9610.css — 200 — 8.7 KiB — 835 ms — h3https://costdown.org/logo-128.png/logo-128.png https://costdown.org/logo-128.png — 200 — 10.5 KiB — 856 ms — h3https://costdown.org/_next/static/chunks/webpack-acb34275d54b1fbc.js/_next/static/chunks/webpack-acb342... https://costdown.org/_next/static/chunks/webpack-acb34275d54b1fbc.js — 200 — 3.3 KiB — 677 ms — h3https://costdown.org/_next/static/chunks/4bd1b696-f785427dddbba9fb.js/_next/static/chunks/4bd1b696-f7854... https://costdown.org/_next/static/chunks/4bd1b696-f785427dddbba9fb.js — 200 — 54.2 KiB — 977 ms — h3https://costdown.org/_next/static/chunks/1255-fc6c00ab2f765339.js/_next/static/chunks/1255-fc6c00ab2... https://costdown.org/_next/static/chunks/1255-fc6c00ab2f765339.js — 200 — 46.5 KiB — 969 ms — h3https://costdown.org/_next/static/chunks/main-app-05a5fe279f4f6e20.js/_next/static/chunks/main-app-05a5f... https://costdown.org/_next/static/chunks/main-app-05a5fe279f4f6e20.js — 200 — 1.3 KiB — 702 ms — h3https://costdown.org/_next/static/chunks/2619-3c9e02e22d10480a.js/_next/static/chunks/2619-3c9e02e22... https://costdown.org/_next/static/chunks/2619-3c9e02e22d10480a.js — 200 — 4.4 KiB — 651 ms — h3https://costdown.org/_next/static/chunks/8009-265e6cb796d00673.js/_next/static/chunks/8009-265e6cb79... https://costdown.org/_next/static/chunks/8009-265e6cb796d00673.js — 200 — 148.5 KiB — 1.2 s — h3https://costdown.org/_next/static/chunks/2337-d8f99f4e41701169.js/_next/static/chunks/2337-d8f99f4e4... https://costdown.org/_next/static/chunks/2337-d8f99f4e41701169.js — 200 — 4.2 KiB — 682 ms — h3https://costdown.org/_next/static/chunks/app/%5Blang%5D/layout-a1ce92e8d46a0a79.js/_next/static/chunks/app/%5Blang%5D... https://costdown.org/_next/static/chunks/app/%5Blang%5D/layout-a1ce92e8d46a0a79.js — 200 — 3.7 KiB — 701 ms — h3https://costdown.org/_next/static/chunks/5905-66bd670be201cd25.js/_next/static/chunks/5905-66bd670be... https://costdown.org/_next/static/chunks/5905-66bd670be201cd25.js — 200 — 20.3 KiB — 868 ms — h3https://costdown.org/_next/static/chunks/app/%5Blang%5D/page-778be06fec310a48.js/_next/static/chunks/app/%5Blang%5D... https://costdown.org/_next/static/chunks/app/%5Blang%5D/page-778be06fec310a48.js — 200 — 1.7 KiB — 658 ms — h3https://static.cloudflareinsights.com/beacon.min.js/v4513226cdae34746b4dedf0b4dfa099e1781791509496static.cloudflareinsights.com/beaco... https://static.cloudflareinsights.com/beacon.min.js/v4513226cdae34746b4dedf0b4dfa099e1781791509496 — 200 — 11.3 KiB — 29 ms — h2https://costdown.org/_next/static/media/df0a9ae256c0569c-s.woff2/_next/static/media/df0a9ae256c0569... https://costdown.org/_next/static/media/df0a9ae256c0569c-s.woff2 — 200 — 11.1 KiB — 828 ms — h3https://costdown.org/_next/static/media/21350d82a1f187e9-s.woff2/_next/static/media/21350d82a1f187e... https://costdown.org/_next/static/media/21350d82a1f187e9-s.woff2 — 200 — 19.4 KiB — 855 ms — h3https://costdown.org/cdn-cgi/rum?/cdn-cgi/rum? https://costdown.org/cdn-cgi/rum? — 204 — 445 B — 10 ms — h3https://costdown.org/favicon.ico/favicon.ico https://costdown.org/favicon.ico — 200 — 14.0 KiB — 384 ms — h3https://costdown.org/login?_rsc=XSA5kkUCbk8ea1m8/login?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/login?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.2 KiB — 219 ms — h3https://costdown.org/register?_rsc=XSA5kkUCbk8ea1m8/register?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/register?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.3 KiB — 212 ms — h3https://costdown.org/write?_rsc=XSA5kkUCbk8ea1m8/write?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/write?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.3 KiB — 214 ms — h3
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Image Optimization
1 images, 4 KB total, 0 KB wasted
INFO

Image Optimization Audit

Total Images

1

Total Size

4 KB

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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