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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
97
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
75
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
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.

874 ms

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

1.02 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.

0.001

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

1.36 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.

1.02 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
96% third-party, 0 ms blocking
FIX
96% third-party, 0 ms blocking
Warning::
Third-party code accounts for 96% of page weight (1.4 MiB of 1.4 MiB)
Info::
Third-party blocking time is low (0 ms)
96%
First-party Third-party
D
JS Bundles
Action
16 scripts, 406 KB unused
FIX
16 scripts, 406 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...: 62 KB unused (41%)
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: 406 KB
406 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 KB62 KB (41%)✓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
1.4 MB transferred, 60 requests
REVIEW
1.4 MB transferred, 60 requests
Info::
Page weighs 3.6 MB (1.4 MB transferred)
Warning::
JavaScript is 668 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 668 KB
Info::
60 HTTP requests
Info::
Estimated 0.30 g CO2 per page load
1.4 MB / 2.4 MB budget
1.4 MB transferred
60 requests
0.30 g CO2 per page load
JavaScript 668.4 KiB 46%
Images 608.7 KiB 42%
CSS 112.9 KiB 8%
HTML 47.2 KiB 3%
Other 11.0 KiB 1%
Other 1.4 KiB 0%
Other 346 B 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
30 images, 0 KB saveable
REVIEW
30 images, 0 KB saveable
Info::
All images are well-optimized
30 images 609 KB
0 oversized -0 KB
6 legacy format
0 missing dimensions CLS risk
B
JS Execution Cost
503ms total JS execution
REVIEW
503ms total JS execution
Warning::
https://dev.to/: 272ms CPU time
Info::
Unattributable: 116ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-TYEM...: 61ms CPU time
Info::
https://assets.dev.to/assets/base-0c748bbcdc300412...: 53ms CPU time
Info::
Third-party scripts: 231ms (46% of total)

Main Thread Breakdown

Script Evaluation 28% Style & Layout 28% Other 22% Script Parsing & Compilation 11% Parse HTML & CSS 6% Rendering 5%
ScriptTotalScriptingParse/CompileParty
https://dev.to/272ms11ms1ms1st
Unattributable116ms4ms0ms3rd
https://www.googletagmanager.com/gtag/js?id=G-TYEM8Y3JN361ms45ms15ms3rd
https://assets.dev.to/assets/base-0c748bbcdc30041261c326ef2ce931fbce46c58bc3c488da881ae35c4750941d.js53ms38ms7ms3rd
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
60 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
46% of JavaScript execution is third-party
First-party Third-party 231ms · 200KB · €2/mo
Unattributable
Other
Optional
Execution 116ms
Transfer 0 KB
Monthly Cost €1/mo
Google Tag Manager
Tag Manager
Optional
Execution 61ms
Transfer 151 KB
Unused 41%
Monthly Cost €1/mo
assets.dev.to
Other
Optional
Execution 53ms
Transfer 50 KB
Unused 71%
Monthly Cost €1/mo

46% 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

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

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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