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Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
90
GRADE
A
FIX
1
REVIEW
5
PASS
8
INFO
2

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

Mobile Desktop
95
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
81
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.
83
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.

1.97 s

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

2.58 s

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

54 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.009

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

1.97 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.

3.51 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
16
8 PASS 5 REVIEW 1 FIX
D
HTTP Caching
Action
No cache headers
FIX
No cache headers
Warning::
No Cache-Control header found
Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.
Info::
ETag present — enables conditional (304) responses
Info::
Last-Modified header present

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

B
Third-Party Impact
48% third-party, 0 ms blocking
REVIEW
48% third-party, 0 ms blocking
Info::
Third-party code accounts for 48% of page weight (151.8 KiB of 318.1 KiB)
Info::
Third-party blocking time is low (0 ms)
52%
48%
First-party Third-party
B
Image Optimization
4 images, 0 KB saveable
REVIEW
4 images, 0 KB saveable
Warning::
https://www.clojure.org/images/clojure-logo-120b.p... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.clojure.org/images/clojuretv.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
4 images 88 KB
0 oversized -0 KB
4 legacy format
2 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

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

B
JS Execution Cost
805ms total JS execution
REVIEW
805ms total JS execution
Warning::
https://www.clojure.org/: 293ms CPU time
Info::
https://cdn.matomo.cloud/cognitect.matomo.cloud/ma...: 168ms CPU time
Info::
Unattributable: 149ms CPU time
Info::
https://www.clojure.org/js/webflow.js: 104ms CPU time
Info::
https://ajax.googleapis.com/ajax/libs/jquery/1.11....: 91ms CPU time
Warning::
Third-party scripts: 408ms (51% of total)

Main Thread Breakdown

Script Evaluation 35% Style & Layout 31% Other 21% Script Parsing & Compilation 6% Rendering 4%
ScriptTotalScriptingParse/CompileParty
https://www.clojure.org/293ms7ms2ms1st
https://cdn.matomo.cloud/cognitect.matomo.cloud/matomo.js168ms141ms20ms3rd
Unattributable149ms13ms0ms3rd
https://www.clojure.org/js/webflow.js104ms48ms18ms1st
https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js91ms67ms10ms3rd
B
JS Bundles
6 scripts, 53 KB unused
REVIEW
6 scripts, 53 KB unused
Warning::
https://cdn.matomo.cloud/cognitect.matomo.cloud/ma...: 33 KB unused (58%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.clojure.org/js/webflow.js: 20 KB unused (57%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.clojure.org/js/webflow.js: unminified — 13 KB could be saved
Info::
Total unused JavaScript: 53 KB
53 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://cdn.matomo.cloud/cognitect.matomo.cloud/matomo.js57 KB33 KB (58%)✓3rd
https://www.clojure.org/js/webflow.js35 KB20 KB (57%)✗1st
https://www.clojure.org/js/modernizr.js3 KB—✓1st
https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js33 KB—✓3rd
https://www.clojure.org/js/highlight.pack.js12 KB—✓1st
https://cognitect.matomo.cloud/plugins/HeatmapSessionRecording/configs.php?idsite=9&trackerid=u4DPPO&url=https%3A%2F%2Fwww.clojure.org%2F0 KB—✓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

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

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
318 KB transferred, 25 requests
PASS
318 KB transferred, 25 requests
Info::
Page weighs 783 KB (318 KB transferred)
Info::
25 HTTP requests
Info::
Estimated 0.07 g CO2 per page load
318 KB / 2.4 MB budget
318 KB transferred
25 requests
0.07 g CO2 per page load
JavaScript 140.2 KiB 44%
Images 88.2 KiB 28%
Fonts 58.0 KiB 18%
CSS 21.2 KiB 7%
HTML 6.3 KiB 2%
Other 2.4 KiB 1%
Other 1.7 KiB 1%
Other 145 B 0%
0 2.4 MB 4.9 MB
Under budget
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+
Font Loading
3 fonts (58 KB)
PASS
3 fonts (58 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

58 KB total

Render-blocking

0

of 3

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s 2.0 s 2.5 s FCP 2.0 s LCP 2.6 shttps://fonts.gstatic.com/s/opensans/v44/memvYaGs126MiZpBA-UvWbX2vVnXBbObj2OVTS-mu0SC55I.woff2memvYaGs126MiZpBA-UvWbX... https://fonts.gstatic.com/s/opensans/v44/memvYaGs126MiZpBA-UvWbX2vVnXBbObj2OVTS-mu0SC55I.woff2 — 42.0 KiB — 0 ms — font-display: swaphttps://www.clojure.org/fonts/icofont.woff2icofont.woff2 https://www.clojure.org/fonts/icofont.woff2 — 2.1 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/ptserif/v19/EJRTQgYoZZY2vCFuvAFT_r21cgT9rcs.woff2EJRTQgYoZZY2vCFuvAFT_r2... https://fonts.gstatic.com/s/ptserif/v19/EJRTQgYoZZY2vCFuvAFT_r21cgT9rcs.woff2 — 13.9 KiB — 0 ms — font-display: swap
memvYaGs126MiZpBA-UvWbX... woff2 swap
Size 42 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
icofont.woff2 woff2 swap
Size 2 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
EJRTQgYoZZY2vCFuvAFT_r2... woff2 swap
Size 14 KB
Load time 0 ms
Start 0 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+
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+
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
Network Waterfall
25 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
51% of JavaScript execution is third-party
First-party Third-party 408ms · 90KB · €4/mo
Matomo
Analytics
Optional
Execution 168ms
Transfer 57 KB
Unused 58%
Monthly Cost €2/mo
Unattributable
Other
Optional
Execution 149ms
Transfer 0 KB
Monthly Cost €2/mo
ajax.googleapis.com
Other
Optional
Execution 91ms
Transfer 33 KB
Monthly Cost €1/mo

51% 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

58% of Matomo's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

How third-party costs are calculated

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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