Skip to content
https://costdown.org

Performance

· 25 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
96
GRADE
A
FIX
1
REVIEW
2
PASS
20
INFO
2

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

Mobile Desktop
90
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.
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.

1.10 s

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

3.58 s

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

89 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.

2.31 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.

3.58 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
20 PASS 2 REVIEW 1 FIX
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
C
JS Execution Cost
Action
1527ms total JS execution
REVIEW
1527ms total JS execution
Warning::
https://costdown.org/_next/static/chunks/1255-fc6c...: 889ms CPU time
Warning::
https://costdown.org/: 304ms CPU time
Info::
Unattributable: 202ms CPU time
Info::
https://costdown.org/_next/static/chunks/8009-3f14...: 80ms CPU time
Info::
https://costdown.org/_next/static/chunks/4bd1b696-...: 52ms CPU time

Main Thread Breakdown

Script Evaluation 59% Other 15% Style & Layout 13% Script Parsing & Compilation 7% Garbage Collection 4%
ScriptTotalScriptingParse/CompileParty
https://costdown.org/_next/static/chunks/1255-fc6c00ab2f765339.js889ms794ms10ms1st
https://costdown.org/304ms38ms18ms1st
Unattributable202ms16ms0ms1st
https://costdown.org/_next/static/chunks/8009-3f143f2ef12c5b60.js80ms31ms49ms1st
https://costdown.org/_next/static/chunks/4bd1b696-f785427dddbba9fb.js52ms24ms16ms1st
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.
A+
Page Weight Budget
541 KB transferred, 23 requests
PASS
541 KB transferred, 23 requests
Info::
Page weighs 1.3 MB (541 KB transferred)
Info::
Fonts are 214 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 214 KB
Info::
23 HTTP requests
Info::
Estimated 0.11 g CO2 per page load
541 KB / 2.4 MB budget
541 KB transferred
23 requests
0.11 g CO2 per page load
JavaScript 283.1 KiB 52%
Fonts 214.3 KiB 40%
HTML 15.9 KiB 3%
Images 9.8 KiB 2%
CSS 8.6 KiB 2%
Other 6.0 KiB 1%
Other 3.4 KiB 1%
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
No third-party resources
PASS
No third-party resources
Info::
No third-party resources detected
No third-party resources detected — all resources are first-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 (214 KB)
PASS
6 fonts (214 KB)
Info::
6 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

6

214 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 FCP 1.1 s LCP 3.6 shttps://costdown.org/_next/static/media/62c97acc3aa63787-s.p.woff262c97acc3aa63787-s.p.woff2 https://costdown.org/_next/static/media/62c97acc3aa63787-s.p.woff2 — 12.6 KiB — 30 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 — 83.7 KiB — 85 ms — 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 — 39.9 KiB — 85 ms — 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 — 47.6 KiB — 86 ms — font-display: swaphttps://costdown.org/_next/static/media/df0a9ae256c0569c-s.woff2df0a9ae256c0569c-s.woff2 https://costdown.org/_next/static/media/df0a9ae256c0569c-s.woff2 — 11.2 KiB — 32 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 — 32 ms — font-display: swap
62c97acc3aa63787-s.p.woff2 woff2 swap
Size 13 KB
Load time 30 ms
Start 164 ms
Risk FOUT — text flashes from fallback to web font
8e9860b6e62d6359-s.p.woff2 woff2 swap
Size 84 KB
Load time 85 ms
Start 165 ms
Risk FOUT — text flashes from fallback to web font
bb3ef058b751a6ad-s.p.woff2 woff2 swap
Size 40 KB
Load time 85 ms
Start 165 ms
Risk FOUT — text flashes from fallback to web font
e4af272ccee01ff0-s.p.woff2 woff2 swap
Size 48 KB
Load time 86 ms
Start 166 ms
Risk FOUT — text flashes from fallback to web font
df0a9ae256c0569c-s.woff2 woff2 swap
Size 11 KB
Load time 32 ms
Start 315 ms
Risk FOUT — text flashes from fallback to web font
21350d82a1f187e9-s.woff2 woff2 swap
Size 19 KB
Load time 32 ms
Start 317 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+
JS Bundles
10 scripts, 0 KB unused
PASS
10 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.js46 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/8009-3f143f2ef12c5b60.js148 KB—✓1st
https://costdown.org/_next/static/chunks/2337-8f491b67f44c9a7e.js4 KB—✓1st
https://costdown.org/_next/static/chunks/app/%5Blang%5D/layout-558c75ed1ffbb746.js3 KB—✓1st
https://costdown.org/_next/static/chunks/5905-8122912d4be580e7.js20 KB—✓1st
https://costdown.org/_next/static/chunks/app/%5Blang%5D/page-778be06fec310a48.js1 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 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
23 resources · 541 KB · 0 KB savings available
PASS
23 resources · 541 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 541 KB
23 resources · 541.1 KiB · 0 third-party Within 1MB page-weight target
JavaScript 52% · 283.1 KiB
Font 40% · 214.3 KiB
Document 3% · 15.9 KiB
Image 3% · 15.8 KiB
CSS 2% · 8.6 KiB
Other 1% · 3.4 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
23 requests over 1500ms
INFO
0 ms 1.0 s 2.0 s 3.0 s FCP 1.1 s LCP 3.6 shttps://costdown.org// https://costdown.org/ — 200 — 15.9 KiB — 597 ms — h2https://costdown.org/_next/static/media/62c97acc3aa63787-s.p.woff2/_next/static/media/62c97acc3aa6378... https://costdown.org/_next/static/media/62c97acc3aa63787-s.p.woff2 — 200 — 12.6 KiB — 30 ms — h2https://costdown.org/_next/static/media/8e9860b6e62d6359-s.p.woff2/_next/static/media/8e9860b6e62d635... https://costdown.org/_next/static/media/8e9860b6e62d6359-s.p.woff2 — 200 — 83.7 KiB — 85 ms — h2https://costdown.org/_next/static/media/bb3ef058b751a6ad-s.p.woff2/_next/static/media/bb3ef058b751a6a... https://costdown.org/_next/static/media/bb3ef058b751a6ad-s.p.woff2 — 200 — 39.9 KiB — 85 ms — h2https://costdown.org/_next/static/media/e4af272ccee01ff0-s.p.woff2/_next/static/media/e4af272ccee01ff... https://costdown.org/_next/static/media/e4af272ccee01ff0-s.p.woff2 — 200 — 47.6 KiB — 86 ms — h2https://costdown.org/_next/static/css/70421232ac481db0.css/_next/static/css/70421232ac481db0.... https://costdown.org/_next/static/css/70421232ac481db0.css — 200 — 8.6 KiB — 74 ms — h2https://costdown.org/logo-128.png/logo-128.png https://costdown.org/logo-128.png — 200 — 9.8 KiB — 210 ms — h2https://costdown.org/_next/static/chunks/webpack-acb34275d54b1fbc.js/_next/static/chunks/webpack-acb342... https://costdown.org/_next/static/chunks/webpack-acb34275d54b1fbc.js — 200 — 2.7 KiB — 75 ms — h2https://costdown.org/_next/static/chunks/4bd1b696-f785427dddbba9fb.js/_next/static/chunks/4bd1b696-f7854... https://costdown.org/_next/static/chunks/4bd1b696-f785427dddbba9fb.js — 200 — 54.0 KiB — 78 ms — h2https://costdown.org/_next/static/chunks/1255-fc6c00ab2f765339.js/_next/static/chunks/1255-fc6c00ab2... https://costdown.org/_next/static/chunks/1255-fc6c00ab2f765339.js — 200 — 46.0 KiB — 78 ms — h2https://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 — 1.1 KiB — 76 ms — h2https://costdown.org/_next/static/chunks/2619-3c9e02e22d10480a.js/_next/static/chunks/2619-3c9e02e22... https://costdown.org/_next/static/chunks/2619-3c9e02e22d10480a.js — 200 — 3.6 KiB — 76 ms — h2https://costdown.org/_next/static/chunks/8009-3f143f2ef12c5b60.js/_next/static/chunks/8009-3f143f2ef... https://costdown.org/_next/static/chunks/8009-3f143f2ef12c5b60.js — 200 — 148.3 KiB — 81 ms — h2https://costdown.org/_next/static/chunks/2337-8f491b67f44c9a7e.js/_next/static/chunks/2337-8f491b67f... https://costdown.org/_next/static/chunks/2337-8f491b67f44c9a7e.js — 200 — 3.7 KiB — 212 ms — h2https://costdown.org/_next/static/chunks/app/%5Blang%5D/layout-558c75ed1ffbb746.js/_next/static/chunks/app/%5Blang%5D... https://costdown.org/_next/static/chunks/app/%5Blang%5D/layout-558c75ed1ffbb746.js — 200 — 3.1 KiB — 211 ms — h2https://costdown.org/_next/static/chunks/5905-8122912d4be580e7.js/_next/static/chunks/5905-8122912d4... https://costdown.org/_next/static/chunks/5905-8122912d4be580e7.js — 200 — 19.7 KiB — 78 ms — h2https://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 — 890 B — 78 ms — h2https://costdown.org/_next/static/media/df0a9ae256c0569c-s.woff2/_next/static/media/df0a9ae256c0569... https://costdown.org/_next/static/media/df0a9ae256c0569c-s.woff2 — 200 — 11.2 KiB — 32 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 — 32 ms — h3https://costdown.org/favicon.ico/favicon.ico https://costdown.org/favicon.ico — 200 — 6.0 KiB — 49 ms — h3https://costdown.org/login?_rsc=XSA5kkUCbk8ea1m8/login?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/login?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.1 KiB — 182 ms — h3https://costdown.org/register?_rsc=XSA5kkUCbk8ea1m8/register?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/register?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.2 KiB — 191 ms — h3https://costdown.org/write?_rsc=XSA5kkUCbk8ea1m8/write?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/write?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.1 KiB — 181 ms — h3
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Image Optimization
1 images, 9 KB total, 9 KB wasted
INFO

Image Optimization Audit

Total Images

1

Total Size

9 KB

Oversized

1

Wasted

9 KB

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

Send Feedback