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https://letsencrypt.org

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
83
GRADE
B
FIX
0
REVIEW
4
PASS
8
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.
93
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.

334 ms

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

950 ms

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

70 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.

680 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.

1.40 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
8 PASS 4 REVIEW
C
Image Optimization
Action
7 images, 0 KB saveable
REVIEW
7 images, 0 KB saveable
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.
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.
7 images 261 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.js3 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.js1 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
949 KB transferred, 24 requests
PASS
949 KB transferred, 24 requests
Info::
Page weighs 2.2 MB (949 KB transferred)
Info::
24 HTTP requests
Info::
Estimated 0.19 g CO2 per page load
949 KB / 2.4 MB budget
949 KB transferred
24 requests
0.19 g CO2 per page load
JavaScript 457.6 KiB 48%
Images 260.9 KiB 27%
Other 172.8 KiB 18%
CSS 39.5 KiB 4%
HTML 16.0 KiB 2%
Other 2.3 KiB 0%
0 2.4 MB 4.9 MB
Under budget
A
Third-Party Impact
31% third-party, 0 ms blocking
PASS
31% third-party, 0 ms blocking
Info::
Third-party code accounts for 31% of page weight (290.0 KiB of 949.1 KiB)
Info::
Third-party blocking time is low (0 ms)
69%
31%
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+
JS Execution Cost
479ms total JS execution
PASS
479ms total JS execution
Warning::
https://letsencrypt.org/js/plotly-min.js: 310ms CPU time
Info::
https://letsencrypt.org/: 117ms CPU time
Info::
Unattributable: 52ms CPU time
Info::
Third-party scripts: 52ms (11% of total)

Main Thread Breakdown

Script Evaluation 51% Other 17% Style & Layout 16% Script Parsing & Compilation 7% Rendering 6%
ScriptTotalScriptingParse/CompileParty
https://letsencrypt.org/js/plotly-min.js310ms256ms36ms1st
https://letsencrypt.org/117ms4ms1ms1st
Unattributable52ms2ms0ms3rd
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
11% of JavaScript execution is third-party
First-party Third-party 52ms · 0KB · $0/mo
Unattributable
Other
Optional
Execution 52ms
Transfer 0 KB
Monthly Cost $0/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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