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Performance

· 21 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
97
GRADE
A+
FIX
1
REVIEW
1
PASS
17
INFO
2

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

Mobile Desktop
98
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.
92
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.

596 ms

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

1.14 s

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

0 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.

596 ms

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

1.14 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
21
17 PASS 1 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
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
550 KB transferred, 30 requests
PASS
550 KB transferred, 30 requests
Info::
Page weighs 1.3 MB (550 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::
30 HTTP requests
Info::
Estimated 0.11 g CO2 per page load
550 KB / 2.4 MB budget
550 KB transferred
30 requests
0.11 g CO2 per page load
JavaScript 287.4 KiB 52%
Fonts 216.8 KiB 39%
HTML 14.9 KiB 3%
Other 11.4 KiB 2%
CSS 8.8 KiB 2%
Other 6.0 KiB 1%
Images 4.8 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 5 KB
0 oversized -0 KB
1 legacy format
0 missing dimensions CLS risk
A+
JS Execution Cost
231ms total JS execution
PASS
231ms total JS execution
Info::
https://costdown.org/: 111ms CPU time
Info::
https://costdown.org/_next/static/chunks/1255-fc6c...: 67ms CPU time
Info::
Unattributable: 53ms CPU time

Main Thread Breakdown

Style & Layout 34% Script Evaluation 32% Other 19% Script Parsing & Compilation 11%
ScriptTotalScriptingParse/CompileParty
https://costdown.org/111ms3ms3ms1st
https://costdown.org/_next/static/chunks/1255-fc6c00ab2f765339.js67ms60ms5ms1st
Unattributable53ms10ms0ms1st
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 500 ms 1.0 s FCP 596 ms LCP 1.1 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 — 64 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 — 65 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 — 40.6 KiB — 59 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 — 48.4 KiB — 76 ms — 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 — 30 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 — 35 ms — font-display: swap
62c97acc3aa63787-s.p.woff2 woff2 swap
Size 13 KB
Load time 64 ms
Start 149 ms
Risk FOUT — text flashes from fallback to web font
8e9860b6e62d6359-s.p.woff2 woff2 swap
Size 84 KB
Load time 65 ms
Start 149 ms
Risk FOUT — text flashes from fallback to web font
bb3ef058b751a6ad-s.p.woff2 woff2 swap
Size 41 KB
Load time 59 ms
Start 150 ms
Risk FOUT — text flashes from fallback to web font
e4af272ccee01ff0-s.p.woff2 woff2 swap
Size 48 KB
Load time 76 ms
Start 150 ms
Risk FOUT — text flashes from fallback to web font
df0a9ae256c0569c-s.woff2 woff2 swap
Size 11 KB
Load time 30 ms
Start 282 ms
Risk FOUT — text flashes from fallback to web font
21350d82a1f187e9-s.woff2 woff2 swap
Size 19 KB
Load time 35 ms
Start 283 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.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/8009-3f143f2ef12c5b60.js149 KB—✓1st
https://costdown.org/_next/static/chunks/2337-9e705982e6b7d197.js4 KB—✓1st
https://costdown.org/_next/static/chunks/app/%5Blang%5D/layout-0815a0910f302531.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.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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
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
30 resources · 550 KB · 0 KB savings available
PASS
30 resources · 550 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 550 KB
30 resources · 550.1 KiB · 0 third-party Within 1MB page-weight target
JavaScript 52% · 287.4 KiB
Font 39% · 216.8 KiB
Document 3% · 14.9 KiB
Other 2% · 11.4 KiB
Image 2% · 10.8 KiB
CSS 2% · 8.8 KiB
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
30 requests over 653ms
INFO
0 ms 500 ms 1.0 s FCP 596 ms LCP 1.1 shttps://costdown.org// https://costdown.org/ — 200 — 14.9 KiB — 155 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 — 64 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 — 65 ms — 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 — 59 ms — 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 — 76 ms — h3https://costdown.org/_next/static/css/70421232ac481db0.css/_next/static/css/70421232ac481db0.... https://costdown.org/_next/static/css/70421232ac481db0.css — 200 — 8.8 KiB — 37 ms — h3https://costdown.org/logo-64.png/logo-64.png https://costdown.org/logo-64.png — 200 — 4.8 KiB — 97 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 — 66 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 — 81 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 — 84 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 — 81 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 — 80 ms — h3https://costdown.org/_next/static/chunks/8009-3f143f2ef12c5b60.js/_next/static/chunks/8009-3f143f2ef... https://costdown.org/_next/static/chunks/8009-3f143f2ef12c5b60.js — 200 — 148.7 KiB — 97 ms — h3https://costdown.org/_next/static/chunks/2337-9e705982e6b7d197.js/_next/static/chunks/2337-9e705982e... https://costdown.org/_next/static/chunks/2337-9e705982e6b7d197.js — 200 — 3.9 KiB — 90 ms — h3https://costdown.org/_next/static/chunks/app/%5Blang%5D/layout-0815a0910f302531.js/_next/static/chunks/app/%5Blang%5D... https://costdown.org/_next/static/chunks/app/%5Blang%5D/layout-0815a0910f302531.js — 200 — 3.4 KiB — 94 ms — h3https://costdown.org/_next/static/chunks/5905-8122912d4be580e7.js/_next/static/chunks/5905-8122912d4... https://costdown.org/_next/static/chunks/5905-8122912d4be580e7.js — 200 — 19.9 KiB — 94 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 — 92 ms — h3https://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 — 30 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 — 35 ms — h3https://costdown.org/favicon.ico/favicon.ico https://costdown.org/favicon.ico — 200 — 6.0 KiB — 55 ms — h3https://costdown.org/experts?_rsc=XSA5kkUCbk8ea1m8/experts?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/experts?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.1 KiB — 143 ms — h3https://costdown.org/calculator?_rsc=XSA5kkUCbk8ea1m8/calculator?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/calculator?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.1 KiB — 157 ms — h3https://costdown.org/my-projects?_rsc=XSA5kkUCbk8ea1m8/my-projects?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/my-projects?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.1 KiB — 157 ms — h3https://costdown.org/my-proposals?_rsc=XSA5kkUCbk8ea1m8/my-proposals?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/my-proposals?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.1 KiB — 162 ms — h3https://costdown.org/write?_rsc=XSA5kkUCbk8ea1m8/write?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/write?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.2 KiB — 163 ms — h3https://costdown.org/login?_rsc=XSA5kkUCbk8ea1m8/login?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/login?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.1 KiB — 100 ms — h3https://costdown.org/register?_rsc=XSA5kkUCbk8ea1m8/register?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/register?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.1 KiB — 85 ms — h3https://costdown.org/article/14?_rsc=XSA5kkUCbk8ea1m8/article/14?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/article/14?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.1 KiB — 89 ms — h3https://costdown.org/article/5?_rsc=XSA5kkUCbk8ea1m8/article/5?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/article/5?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.2 KiB — 75 ms — h3https://costdown.org/article/2?_rsc=XSA5kkUCbk8ea1m8/article/2?_rsc=XSA5kkUCbk8ea1m8 https://costdown.org/article/2?_rsc=XSA5kkUCbk8ea1m8 — 200 — 1.3 KiB — 71 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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