Skip to content
https://www.cncf.io

Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
83
GRADE
B
FIX
2
REVIEW
2
PASS
10
INFO
2

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

Mobile Desktop
79
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
95
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.
100
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.

2.67 s

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

4.26 s

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

94 ms

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

0.001

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

4.37 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.

5.99 s

Page Load Progression

456 ms
911 ms
1.4 s
1.8 s
2.3 s
2.7 s
3.2 s
3.6 s
Checks
16
10 PASS 2 REVIEW 2 FIX
F
Page Weight Budget
Action
3.7 MB transferred, 110 requests
FIX
3.7 MB transferred, 110 requests
Warning::
Page weighs 4.5 MB (3.7 MB transferred)
Warning::
110 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 0.77 g CO2 per page load
3.7 MB / 2.4 MB budget
3.7 MB transferred
110 requests
0.77 g CO2 per page load
Other 2.9 MiB 79%
Images 470.0 KiB 12%
JavaScript 166.0 KiB 4%
Fonts 68.0 KiB 2%
HTML 54.1 KiB 1%
CSS 33.7 KiB 1%
Other 2.7 KiB 0%
Other 1.4 KiB 0%
Other 1.1 KiB 0%
Other 678 B 0%
0 2.4 MB 4.9 MB
Over budget

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Why this matters

High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.

Source: web.dev

D
JS Execution Cost
Action
2949ms total JS execution
FIX
2949ms total JS execution
Warning::
Unattributable: 1236ms CPU time
Warning::
https://www.cncf.io/: 1084ms CPU time
Warning::
https://www.cncf.io/wp/wp-includes/js/jquery/jquer...: 420ms CPU time
Info::
https://lfx-segment.platform.linuxfoundation.org/l...: 115ms CPU time
Info::
https://js-agent.newrelic.com/nr-rum-1.312.1.min.j...: 93ms CPU time
Info::
Third-party scripts: 1444ms (49% of total)

Main Thread Breakdown

Other 48% Script Evaluation 21% Style & Layout 20% Rendering 8%
ScriptTotalScriptingParse/CompileParty
Unattributable1236ms93ms0ms3rd
https://www.cncf.io/1084ms44ms11ms1st
https://www.cncf.io/wp/wp-includes/js/jquery/jquery.min.js?ver=3.7.1420ms271ms7ms1st
https://lfx-segment.platform.linuxfoundation.org/latest/lfx-segment-analytics.min.js115ms83ms21ms3rd
https://js-agent.newrelic.com/nr-rum-1.312.1.min.js93ms76ms5ms3rd
C
Image Optimization
Action
82 images, 0 KB saveable
REVIEW
82 images, 0 KB saveable
Warning::
https://www.cncf.io/wp-content/uploads/2024/11/CNC... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.cncf.io/wp-content/uploads/2026/02/CNC... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.cncf.io/wp-content/themes/cncf-twenty-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.cncf.io/wp-content/uploads/2026/02/CNC... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.cncf.io/wp-content/uploads/2026/02/CNC... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
82 images 470 KB
0 oversized -0 KB
77 legacy format
5 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

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

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

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

Green Hosting

No green hosting detected

A+
Third-Party Impact
9% third-party, 0 ms blocking
PASS
9% third-party, 0 ms blocking
Info::
Third-party code accounts for 9% of page weight (328.5 KiB of 3.7 MiB)
Info::
Third-party blocking time is low (0 ms)
91%
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+
Font Loading
4 fonts (68 KB)
PASS
4 fonts (68 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

68 KB total

Render-blocking

0

of 4

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 FCP 2.7 s LCP 4.3 shttps://www.cncf.io/wp-content/themes/cncf-twenty-two/source/fonts/ClarityCity-700.woff2ClarityCity-700.woff2 https://www.cncf.io/wp-content/themes/cncf-twenty-two/source/fonts/ClarityCity-700.woff2 — 17.0 KiB — 0 ms — font-display: swaphttps://www.cncf.io/wp-content/themes/cncf-twenty-two/source/fonts/ClarityCity-600.woff2ClarityCity-600.woff2 https://www.cncf.io/wp-content/themes/cncf-twenty-two/source/fonts/ClarityCity-600.woff2 — 17.2 KiB — 0 ms — font-display: swaphttps://www.cncf.io/wp-content/themes/cncf-twenty-two/source/fonts/ClarityCity-400.woff2ClarityCity-400.woff2 https://www.cncf.io/wp-content/themes/cncf-twenty-two/source/fonts/ClarityCity-400.woff2 — 16.7 KiB — 0 ms — font-display: swaphttps://www.cncf.io/wp-content/themes/cncf-twenty-two/source/fonts/ClarityCity-800.woff2ClarityCity-800.woff2 https://www.cncf.io/wp-content/themes/cncf-twenty-two/source/fonts/ClarityCity-800.woff2 — 17.2 KiB — 0 ms — font-display: swap
ClarityCity-700.woff2 woff2 swap
Size 17 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
ClarityCity-600.woff2 woff2 swap
Size 17 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
ClarityCity-400.woff2 woff2 swap
Size 17 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
ClarityCity-800.woff2 woff2 swap
Size 17 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+
JS Bundles
13 scripts, 27 KB unused
PASS
13 scripts, 27 KB unused
Warning::
https://lfx-segment.platform.linuxfoundation.org/l...: 27 KB unused (34%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 27 KB
27 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://lfx-segment.platform.linuxfoundation.org/latest/lfx-segment-analytics.min.js83 KB27 KB (34%)✓3rd
https://www.cncf.io/wp-content/plugins/flying-pages/flying-pages.min.js?ver=2.4.71 KB—✓1st
https://www.cncf.io/wp-content/themes/cncf-twenty-two/build/globals.min.js?ver=17755515423 KB—✓1st
https://www.cncf.io/wp-content/themes/cncf-twenty-two/source/js/on-demand/video.js?ver=17755515481 KB—✓1st
https://www.cncf.io/wp-content/themes/cncf-twenty-two/source/js/libraries/purecounter.min.js?ver=17755515483 KB—✓1st
https://www.cncf.io/wp/wp-includes/js/jquery/jquery.min.js?ver=3.7.135 KB—✓1st
https://www.cncf.io/wp-content/themes/cncf-twenty-two/source/js/libraries/slick.min.js?ver=177555154813 KB—✓1st
https://www.cncf.io/wp-content/themes/cncf-twenty-two/source/js/on-demand/slick-config.js?ver=17755515481 KB—✓1st
https://www.cncf.io/wp-content/themes/cncf-twenty-two/source/js/on-demand/slick-events-config.js?ver=17755515481 KB—✓1st
https://www.cncf.io/wp-content/themes/cncf-twenty-two/source/js/on-demand/home-terminal.js?ver=17755515481 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

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
16 hints, 0 missing preconnects
PASS
16 hints, 0 missing preconnects
Info::
Page uses 16 resource hint(s)

Current Resource Hints

preconnect
+2
12
preload
1
dns-prefetch
3
prefetch
—

16 resource hints configured

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+
HTTP Caching
max-age=60 (1 minute)
PASS
max-age=60 (1 minute)
Info::
Cache-Control header is set
Got: public, max-age=60, s-maxage=43200, stale-while-revalidate=86400, stale-if-error=604800
Info::
Effective TTL: 1 minute (max-age=60)
Info::
CDN TTL: 12 hours (s-maxage=43200)
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

public, max-age=60, s-maxage=43200, stale-while-revalidate=86400, stale-if-error=604800

DirectiveValueMeaning
public—Any cache may store this response
max-age60Cache for 1 minute
s-maxage43200CDN caches for 12 hours
stale-while-revalidate86400Serve stale for 1 day while fetching fresh
stale-if-error604800
Effective TTL: 60 seconds
Network Waterfall
110 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
49% of JavaScript execution is third-party
First-party Third-party 1444ms · 101KB · $27/mo
Unattributable
Other
Costly
Execution 1236ms
Transfer 0 KB
Monthly Cost $23/mo
lfx-segment.platform.linuxfoundation.org
Other
Optional
Execution 115ms
Transfer 83 KB
Unused 34%
Monthly Cost $2/mo
js-agent.newrelic.com
Other
Optional
Execution 93ms
Transfer 18 KB
Monthly Cost $2/mo

These scripts may cost more than they're worth

  • Unattributable adds 1236ms and costs ~$23/month

49% 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

Unattributable takes 1236ms 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

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

Send Feedback