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https://elixir-lang.org

Performance

· 13 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
95
GRADE
A
FIX
0
REVIEW
2
PASS
10
INFO
1

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

Mobile Desktop
100
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
94
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.

510 ms

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

734 ms

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.

0.002

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

510 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.

734 ms

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
13
10 PASS 2 REVIEW
C
Image Optimization
Action
9 images, 0 KB saveable
REVIEW
9 images, 0 KB saveable
Warning::
https://elixir-lang.org/images/logo/logo.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://elixir-lang.org/images/logo/eef.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
9 images 175 KB
0 oversized -0 KB
9 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

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

Green Hosting

No green hosting detected

A+
Page Weight Budget
265 KB transferred, 21 requests
PASS
265 KB transferred, 21 requests
Info::
Page weighs 376 KB (265 KB transferred)
Info::
21 HTTP requests
Info::
Estimated 0.05 g CO2 per page load
265 KB / 2.4 MB budget
265 KB transferred
21 requests
0.05 g CO2 per page load
Images 175.1 KiB 66%
JavaScript 37.3 KiB 14%
Fonts 33.4 KiB 13%
CSS 8.7 KiB 3%
HTML 6.9 KiB 3%
Other 3.4 KiB 1%
Other 504 B 0%
0 2.4 MB 4.9 MB
Under budget
A
Third-Party Impact
26% third-party, 0 ms blocking
PASS
26% third-party, 0 ms blocking
Info::
Third-party code accounts for 26% of page weight (70.1 KiB of 265.2 KiB)
Info::
Third-party blocking time is low (0 ms)
74%
26%
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
No JS execution data
PASS
No JS execution data
Info::
No significant JS execution detected

Main Thread Breakdown

Other 36% Style & Layout 35% Script Evaluation 17% Rendering 6% Parse HTML & CSS 3%
A+
Font Loading
1 fonts (33 KB)
PASS
1 fonts (33 KB)
Info::
1 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

1

33 KB total

Render-blocking

0

of 1

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 510 ms LCP 734 mshttps://fonts.gstatic.com/s/bitter/v40/rax8HiqOu8IVPmn7f4xpLjpSmw.woff2rax8HiqOu8IVPmn7f4xpLjp... https://fonts.gstatic.com/s/bitter/v40/rax8HiqOu8IVPmn7f4xpLjpSmw.woff2 — 33.4 KiB — 0 ms — font-display: swap
rax8HiqOu8IVPmn7f4xpLjp... woff2 swap
Size 33 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
3 scripts, 20 KB unused
PASS
3 scripts, 20 KB unused
Warning::
https://ajax.googleapis.com/ajax/libs/jquery/1.11....: 20 KB unused (62%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 20 KB
20 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js33 KB20 KB (62%)✓3rd
https://plausible.io/js/plausible.js2 KB—✓3rd
https://elixir-lang.org/js/index.js2 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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A+
HTTP Caching
max-age=600 (10 minutes)
PASS
max-age=600 (10 minutes)
Info::
Cache-Control header is set
Got: max-age=600
Info::
Effective TTL: 10 minutes (max-age=600)
Info::
ETag present — enables conditional (304) responses
Info::
Last-Modified header present
Cache-Control

max-age=600

DirectiveValueMeaning
max-age600Cache for 10 minutes
Effective TTL: 600 seconds
Network Waterfall
21 requests over 0ms
INFO

Performance analysis not available for this result.

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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