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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
80
GRADE
B
FIX
2
REVIEW
5
PASS
5
INFO
2

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

Mobile Desktop
58
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
80
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.
92
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.

2.73 s

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

9.09 s

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

474 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.

3.16 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.

9.16 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
5 PASS 5 REVIEW 2 FIX
D
Third-Party Impact
Action
95% third-party, 0 ms blocking
FIX
95% third-party, 0 ms blocking
Warning::
Third-party code accounts for 95% of page weight (1.0 MiB of 1.1 MiB)
Info::
Third-party blocking time is low (0 ms)
95%
First-party Third-party
D
JS Bundles
Action
17 scripts, 407 KB unused
FIX
17 scripts, 407 KB unused
Warning::
https://assets.dev.to/assets/application-0b2686849...: 186 KB unused (98%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://assets.dev.to/assets/homePage-fd5d5a8d3dab...: 124 KB unused (74%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-TYEM...: 63 KB unused (42%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://assets.dev.to/assets/base-0c748bbcdc300412...: 35 KB unused (71%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 407 KB
407 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://assets.dev.to/assets/application-0b268684912bef9b0f23defff01cb608bfc5d5e5610287725e7b686139ae32d3.js191 KB186 KB (98%)✓3rd
https://assets.dev.to/assets/homePage-fd5d5a8d3dabded9230df005c7df04e1ea5e6dd70b8171bd952cf1e48a146c41.js169 KB124 KB (74%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-TYEM8Y3JN3151 KB63 KB (42%)✓3rd
https://assets.dev.to/assets/base-0c748bbcdc30041261c326ef2ce931fbce46c58bc3c488da881ae35c4750941d.js50 KB35 KB (71%)✓3rd
https://assets.dev.to/assets/feedPreviewCards-8d16b0b656456a28c0a290f756cf6e21e19833111c4796f48c631bfea8323d51.js12 KB—✓3rd
https://assets.dev.to/assets/followButtons-a29380c2c88136b97b2b5e63e94614ff7458fc72e07cffa7b6153831c28a40d2.js30 KB—✓3rd
https://assets.dev.to/assets/billboard-365f8f60fc3506e63bc54cc5b0a2e36f4c11024ff6a30dccd5462467f24b5215.js5 KB—✓3rd
https://assets.dev.to/assets/homePageFeedShortcuts-f7364bc2d6cb139c03e7fe80e32782ba5af34857d2b308e3caa8d902e579a3af.js9 KB—✓3rd
https://assets.dev.to/assets/baseTracking-b6bf73e5ee66633e151e7d5b7c6bbccedfa4c59e3615be97b98c4c0f543ddae7.js3 KB—✓3rd
https://assets.dev.to/assets/storiesList-b9c50cbd898a3a64258a3a49db1c531651b0a4a11937be35ed4651111802b5b5.js1 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

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

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

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

B
Page Weight Budget
1.1 MB transferred, 54 requests
REVIEW
1.1 MB transferred, 54 requests
Info::
Page weighs 3.2 MB (1.1 MB transferred)
Warning::
JavaScript is 672 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 672 KB
Info::
54 HTTP requests
Info::
Estimated 0.23 g CO2 per page load
1.1 MB / 2.4 MB budget
1.1 MB transferred
54 requests
0.23 g CO2 per page load
JavaScript 672.0 KiB 60%
Images 269.3 KiB 24%
CSS 112.9 KiB 10%
HTML 47.2 KiB 4%
Other 8.2 KiB 1%
Other 1.4 KiB 0%
Other 1.1 KiB 0%
0 2.4 MB 4.9 MB
Under budget

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

B
Image Optimization
24 images, 0 KB saveable
REVIEW
24 images, 0 KB saveable
Info::
All images are well-optimized
24 images 269 KB
0 oversized -0 KB
6 legacy format
0 missing dimensions CLS risk
C
JS Execution Cost
Action
1917ms total JS execution
REVIEW
1917ms total JS execution
Warning::
Unattributable: 458ms CPU time
Warning::
https://dev.to/: 438ms CPU time
Warning::
https://assets.dev.to/assets/base-0c748bbcdc300412...: 381ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-TYEM...: 222ms CPU time
Info::
https://assets.dev.to/assets/homePage-fd5d5a8d3dab...: 195ms CPU time
Warning::
Third-party scripts: 1478ms (77% of total)

Main Thread Breakdown

Script Evaluation 33% Other 24% Style & Layout 19% Script Parsing & Compilation 13% Parse HTML & CSS 6% Rendering 5%
ScriptTotalScriptingParse/CompileParty
Unattributable458ms18ms0ms3rd
https://dev.to/438ms32ms3ms1st
https://assets.dev.to/assets/base-0c748bbcdc30041261c326ef2ce931fbce46c58bc3c488da881ae35c4750941d.js381ms133ms19ms3rd
https://www.googletagmanager.com/gtag/js?id=G-TYEM8Y3JN3222ms160ms60ms3rd
https://assets.dev.to/assets/homePage-fd5d5a8d3dabded9230df005c7df04e1ea5e6dd70b8171bd952cf1e48a146c41.js195ms118ms77ms3rd
https://assets.dev.to/assets/application-0b268684912bef9b0f23defff01cb608bfc5d5e5610287725e7b686139ae32d3.js115ms23ms91ms3rd
https://assets.dev.to/assets/baseTracking-b6bf73e5ee66633e151e7d5b7c6bbccedfa4c59e3615be97b98c4c0f543ddae7.js107ms103ms1ms3rd
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

B
HTTP Caching
public, no-cache
REVIEW
public, no-cache
Info::
Cache-Control header is set
Got: public, no-cache
Info::
ETag present — enables conditional (304) responses
Cache-Control

public, no-cache

DirectiveValueMeaning
public—Any cache may store this response
no-cache—Cache but always revalidate first
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
54 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
77% of JavaScript execution is third-party
First-party Third-party 1478ms · 564KB · €16/mo
Unattributable
Other
Costly
Execution 458ms
Transfer 0 KB
Monthly Cost €5/mo
assets.dev.to
Other
Costly
Execution 381ms
Transfer 50 KB
Unused 71%
Monthly Cost €4/mo
Google Tag Manager
Tag Manager
Costly
Execution 222ms
Transfer 151 KB
Unused 42%
Monthly Cost €2/mo
assets.dev.to
Other
Optional
Execution 195ms
Transfer 169 KB
Unused 74%
Monthly Cost €2/mo
assets.dev.to
Other
Optional
Execution 115ms
Transfer 191 KB
Unused 98%
Monthly Cost €1/mo
assets.dev.to
Other
Optional
Execution 107ms
Transfer 3 KB
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • Unattributable adds 458ms and costs ~€5/month
  • assets.dev.to adds 381ms and costs ~€4/month
  • Google Tag Manager adds 222ms and costs ~€2/month

77% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.

Why this matters

When third-party JS execution time exceeds your own, performance gains from frontend work are capped by code you don't own.

Learn more ▾

Every millisecond of third-party JS competes with your own for main-thread time. If their share is bigger than yours, optimization on your code base barely moves the needle. Audit, defer, or remove third-parties before further frontend optimization. Use Lighthouse's third-party audit to identify the worst offenders.

Source: web.dev

Unattributable takes 458ms 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

assets.dev.to takes 381ms 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

71% of assets.dev.to's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

Google Tag Manager takes 222ms 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

74% of assets.dev.to's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

98% of assets.dev.to's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

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.

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