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https://httpwg.org

Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
98
GRADE
A+
FIX
0
REVIEW
2
PASS
13
INFO
2

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.
85
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.
82
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.

1.19 s

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

1.41 s

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.

0.000

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

1.19 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.

1.42 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
17
13 PASS 2 REVIEW
B
Image Optimization
3 images, 0 KB saveable
REVIEW
3 images, 0 KB saveable
Warning::
https://httpwg.org/assets/http.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://httpwg.org/assets/github.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
3 images 3 KB
0 oversized -0 KB
2 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
56 KB transferred, 9 requests
PASS
56 KB transferred, 9 requests
Info::
Page weighs 251 KB (56 KB transferred)
Info::
9 HTTP requests
Info::
Estimated 0.01 g CO2 per page load
56 KB / 2.4 MB budget
56 KB transferred
9 requests
0.01 g CO2 per page load
CSS 24.7 KiB 44%
JavaScript 23.0 KiB 41%
Images 2.8 KiB 5%
HTML 2.8 KiB 5%
Other 2.6 KiB 5%
0 2.4 MB 4.9 MB
Under budget
A+
Third-Party Impact
No third-party resources
PASS
No third-party resources
Info::
No third-party resources detected
No third-party resources detected — all resources are first-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
237ms total JS execution
PASS
237ms total JS execution
Info::
Unattributable: 124ms CPU time
Info::
https://httpwg.org/: 112ms CPU time
Warning::
Third-party scripts: 124ms (52% of total)

Main Thread Breakdown

Other 46% Style & Layout 31% Script Evaluation 9% Parse HTML & CSS 8% Script Parsing & Compilation 4%
ScriptTotalScriptingParse/CompileParty
Unattributable124ms7ms0ms3rd
https://httpwg.org/112ms5ms1ms1st
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+
JS Bundles
1 scripts, 0 KB unused
PASS
1 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://httpwg.org/assets/node_modules/bootstrap/dist/js/bootstrap.bundle.min.js23 KB—✓1st
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+
Page Weight Inventory
9 resources · 56 KB · 0 KB savings available
PASS
9 resources · 56 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 56 KB
Info::
1 third-party resources (0% of weight)
9 resources · 55.8 KiB · 1 third-party Within 1MB page-weight target
CSS 44% · 24.7 KiB
JavaScript 41% · 23.0 KiB
Image 10% · 5.3 KiB
Document 5% · 2.8 KiB
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=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
9 requests over 496ms
INFO
0 ms 500 ms 1.0 s FCP 1.2 s LCP 1.4 shttps://httpwg.org// https://httpwg.org/ — 200 — 2.8 KiB — 20 ms — h2https://httpwg.org/assets/node_modules/bootstrap/dist/css/bootstrap.min.css/assets/node_modules/bootstrap/dist... https://httpwg.org/assets/node_modules/bootstrap/dist/css/bootstrap.min.css — 200 — 24.1 KiB — 151 ms — h2https://httpwg.org/assets/site.css/assets/site.css https://httpwg.org/assets/site.css — 200 — 601 B — 132 ms — h2https://httpwg.org/assets/http.svg/assets/http.svg https://httpwg.org/assets/http.svg — 200 — 790 B — 147 ms — h2https://httpwg.org/assets/github.png/assets/github.png https://httpwg.org/assets/github.png — 200 — 2.0 KiB — 140 ms — h2https://httpwg.org/assets/node_modules/bootstrap/dist/js/bootstrap.bundle.min.js/assets/node_modules/bootstrap/dist... https://httpwg.org/assets/node_modules/bootstrap/dist/js/bootstrap.bundle.min.js — 200 — 23.0 KiB — 145 ms — h2data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='…www.w3.org/2000/svg' viewBox='0 0 3... data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='… — 200 — 0 B — 0 ms — datahttps://httpwg.org/assets/favicon/favicon.ico/assets/favicon/favicon.ico https://httpwg.org/assets/favicon/favicon.ico — 200 — 667 B — 137 ms — h2https://httpwg.org/assets/favicon/favicon-32x32.png/assets/favicon/favicon-32x32.png https://httpwg.org/assets/favicon/favicon-32x32.png — 200 — 1.9 KiB — 128 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
52% of JavaScript execution is third-party
First-party Third-party 124ms · 0KB · $2/mo
Unattributable
Other
Optional
Execution 124ms
Transfer 0 KB
Monthly Cost $2/mo

52% 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

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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