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https://letsencrypt.org

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
83
GRADE
B
FIX
1
REVIEW
4
PASS
7
INFO
2

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

Mobile Desktop
73
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.
92
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.

1.08 s

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

3.74 s

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

667 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.

1.63 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.

5.59 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
14
7 PASS 4 REVIEW 1 FIX
D
JS Execution Cost
Action
2070ms total JS execution
FIX
2070ms total JS execution
Warning::
https://letsencrypt.org/js/plotly-min.js: 1167ms CPU time
Warning::
https://letsencrypt.org/: 500ms CPU time
Info::
https://letsencrypt.org/js/number-animation.137c25...: 205ms CPU time
Info::
Unattributable: 198ms CPU time
Info::
Third-party scripts: 198ms (10% of total)

Main Thread Breakdown

Script Evaluation 49% Other 17% Style & Layout 17% Rendering 8% Script Parsing & Compilation 7%
ScriptTotalScriptingParse/CompileParty
https://letsencrypt.org/js/plotly-min.js1167ms958ms138ms1st
https://letsencrypt.org/500ms17ms2ms1st
https://letsencrypt.org/js/number-animation.137c25102252dc89411a5c2d9eb00a383f12425cb7845c8d8ac4c615c0af1f8e.js205ms39ms0ms1st
Unattributable198ms8ms0ms3rd
C
Image Optimization
Action
7 images, 0 KB saveable
REVIEW
7 images, 0 KB saveable
Warning::
https://letsencrypt.org/images/Divvi-Up-Large-Full... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://letsencrypt.org/images/ISRG-Logo-Blue.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://letsencrypt.org/images/letsencrypt-logo-ho... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://letsencrypt.org/images/Prossimo%20Horizont... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
7 images 82 KB
0 oversized -0 KB
7 legacy format
4 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

C
JS Bundles
Action
9 scripts, 204 KB unused
REVIEW
9 scripts, 204 KB unused
Warning::
https://letsencrypt.org/js/plotly-min.js: 204 KB unused (59%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 204 KB
204 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://letsencrypt.org/js/plotly-min.js347 KB204 KB (59%)✓1st
https://letsencrypt.org/js/le-2025-theme.baca0a37d412391799a4e5f6d58968c12b948b4c91c053a3c025ab758ffb70bc.js2 KB—✓1st
https://letsencrypt.org/js/autoanchor.44783525c73cfeef565e5b8441cd42a848cb630d9f365def73edce4867e6f4c8.js0 KB—✓1st
https://letsencrypt.org/js/number-animation.137c25102252dc89411a5c2d9eb00a383f12425cb7845c8d8ac4c615c0af1f8e.js0 KB—✓1st
https://letsencrypt.org/js/stats.js3 KB—✓1st
https://letsencrypt.org/js/main.a572b61495f9d8fe4e5ec075082ddfe85e5a5ff501c15c499d3f2a4bed71afb6fe89e85f3202aa8fdeebcda97645416bfc75683c2d3471485b5668a6d5f98740.js2 KB—✓1st
https://outreach.abetterinternet.org/js/piUtils.js?ver=2021-09-20100 KB—✓3rd
https://pi.pardot.com/pd.js2 KB—✓3rd
https://pi.pardot.com/analytics?ver=3&pi_form=true&visitor_id=&visitor_id_sign=&pi_opt_in=&campaign_id=64423&account_id=1012011&title=&url=https%3A%2F%2Foutreach.abetterinternet.org%2Fl%2F1011011%2F2025-01-14%2F31v6r&referrer=1 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

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

Green Hosting

No green hosting detected

B
HTTP Caching
public,max-age=0,must-revalidate
REVIEW
public,max-age=0,must-revalidate
Info::
Cache-Control header is set
Got: public,max-age=0,must-revalidate
Info::
ETag present — enables conditional (304) responses
Cache-Control

public,max-age=0,must-revalidate

DirectiveValueMeaning
public—Any cache may store this response
max-age0Cache for 0 seconds
must-revalidate—Must recheck with server after expiry
A
Page Weight Budget
771 KB transferred, 24 requests
PASS
771 KB transferred, 24 requests
Info::
Page weighs 2.0 MB (771 KB transferred)
Info::
24 HTTP requests
Info::
Estimated 0.16 g CO2 per page load
771 KB / 2.4 MB budget
771 KB transferred
24 requests
0.16 g CO2 per page load
JavaScript 456.5 KiB 59%
Other 172.8 KiB 22%
Images 81.9 KiB 11%
CSS 40.3 KiB 5%
HTML 16.0 KiB 2%
Other 3.4 KiB 0%
0 2.4 MB 4.9 MB
Under budget
A
Third-Party Impact
38% third-party, 0 ms blocking
PASS
38% third-party, 0 ms blocking
Info::
Third-party code accounts for 38% of page weight (290.0 KiB of 770.9 KiB)
Info::
Third-party blocking time is low (0 ms)
62%
38%
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
No web fonts (system fonts)
PASS
No web fonts (system fonts)
Info::
No web fonts loaded — system fonts are fastest
No web fonts loaded — system fonts are optimal.
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
Network Waterfall
24 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
10% of JavaScript execution is third-party
First-party Third-party 198ms · 0KB · $1/mo
Unattributable
Other
Optional
Execution 198ms
Transfer 0 KB
Monthly Cost $1/mo

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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