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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
65
GRADE
D
FIX
5
REVIEW
1
PASS
6
INFO
2

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

Mobile Desktop
10
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
77
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.

3.74 s

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

4.99 s

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

642 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.653

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

4.51 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.

6.58 s

Page Load Progression

591 ms
1.2 s
1.8 s
2.4 s
3.0 s
3.5 s
4.1 s
4.7 s
Checks
14
6 PASS 1 REVIEW 5 FIX
F
Page Weight Budget
Action
5.8 MB transferred, 195 requests
FIX
5.8 MB transferred, 195 requests
Critical::
Page weighs 14.4 MB (5.8 MB transferred)
Warning::
JavaScript is 3.1 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 3.1 MB
Warning::
Images are 1.3 MB — compress or use modern formats
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Got: 1.3 MB
Info::
Fonts are 935 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 935 KB
Warning::
195 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 1.2 g CO2 per page load
5.8 MB / 2.4 MB budget
5.8 MB transferred
195 requests
1.2 g CO2 per page load
JavaScript 3.1 MiB 54%
Images 1.3 MiB 23%
Fonts 935.3 KiB 16%
CSS 172.3 KiB 3%
Other 125.6 KiB 2%
Other 65.0 KiB 1%
HTML 31.4 KiB 1%
Other 4.4 KiB 0%
Other 592 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over 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

Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.

Why this matters

Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.

Source: web.dev

Subset fonts to include only used characters, or switch to system font stacks.

Why this matters

Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).

Source: web.dev font loading

Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.

Why this matters

High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.

Source: web.dev

D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (5.8 MiB of 5.8 MiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
F
JS Execution Cost
Action
4291ms total JS execution
FIX
4291ms total JS execution
Warning::
https://open.spotifycdn.com/cdn/build/web-player/w...: 2518ms CPU time
Warning::
Unattributable: 553ms CPU time
Warning::
https://open.spotifycdn.com/cdn/build/web-player/e...: 345ms CPU time
Warning::
https://open.spotifycdn.com/cdn/build/web-player/v...: 325ms CPU time
Info::
https://open.spotify.com/: 244ms CPU time
Warning::
Third-party scripts: 4291ms (100% of total)

Main Thread Breakdown

Script Evaluation 59% Other 17% Style & Layout 14% Script Parsing & Compilation 6%
ScriptTotalScriptingParse/CompileParty
https://open.spotifycdn.com/cdn/build/web-player/web-player.3d61412a.js2518ms1551ms114ms3rd
Unattributable553ms138ms0ms3rd
https://open.spotifycdn.com/cdn/build/web-player/encore~web-player.f7595fde.js345ms330ms12ms3rd
https://open.spotifycdn.com/cdn/build/web-player/vendor~web-player.8d647cb6.js325ms259ms40ms3rd
https://open.spotify.com/244ms1ms0ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-PZHN3VD148ms133ms12ms3rd
https://www.gstatic.com/recaptcha/releases/kUYUkUlSyqkjTSMaN2w3RaOh/recaptcha__en.js88ms58ms27ms3rd
https://cdn.cookielaw.org/scripttemplates/202601.2.0/otBannerSdk.js70ms52ms13ms3rd
F
JS Bundles
Action
62 scripts, 2.4 MB unused
FIX
62 scripts, 2.4 MB unused
Warning::
https://open.spotifycdn.com/cdn/build/web-player/w...: 637 KB unused (62%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.gstatic.com/recaptcha/releases/kUYUkUl...: 420 KB unused (49%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.gstatic.com/recaptcha/releases/kUYUkUl...: 420 KB unused (49%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.gstatic.com/recaptcha/releases/kUYUkUl...: 420 KB unused (49%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://open.spotifycdn.com/cdn/build/web-player/v...: 172 KB unused (75%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 2.4 MB
2442 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://open.spotifycdn.com/cdn/build/web-player/web-player.3d61412a.js1022 KB637 KB (62%)✓3rd
https://www.gstatic.com/recaptcha/releases/kUYUkUlSyqkjTSMaN2w3RaOh/recaptcha__en.js0 KB420 KB (49%)✓3rd
https://www.gstatic.com/recaptcha/releases/kUYUkUlSyqkjTSMaN2w3RaOh/recaptcha__en.js852 KB420 KB (49%)✓3rd
https://www.gstatic.com/recaptcha/releases/kUYUkUlSyqkjTSMaN2w3RaOh/recaptcha__en.js363 KB420 KB (49%)✓3rd
https://open.spotifycdn.com/cdn/build/web-player/vendor~web-player.8d647cb6.js230 KB172 KB (75%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-PZHN3VD158 KB83 KB (53%)✓3rd
https://cdn.cookielaw.org/scripttemplates/202601.2.0/otBannerSdk.js128 KB74 KB (58%)✓3rd
https://open.spotifycdn.com/cdn/build/web-player/encore~web-player.f7595fde.js93 KB72 KB (78%)✓3rd
https://open.spotifycdn.com/cdn/build/web-player/dwp-panel-section.b9b814c0.js57 KB50 KB (88%)✓3rd
https://open.spotifycdn.com/cdn/build/web-player/xpui-root-dialogs.c87a21bd.js54 KB41 KB (77%)✓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

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

F
HTTP Caching
Action
No cache headers
FIX
No cache headers
Warning::
No Cache-Control header found
Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

B
Image Optimization
57 images, 0 KB saveable
REVIEW
57 images, 0 KB saveable
Info::
All images are well-optimized
57 images 1.3 MB
0 oversized -0 KB
55 legacy format
0 missing dimensions CLS risk
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
7 fonts (935 KB)
PASS
7 fonts (935 KB)
Info::
7 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

7

935 KB total

Render-blocking

0

of 7

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 1.0 s 2.0 s 3.0 s 4.0 s 5.0 s FCP 3.7 s LCP 5.0 shttps://encore.scdn.co/fonts/SpotifyMixUI-Regular-76c92fb1a35c462f73429fa8865163eb.woff2SpotifyMixUI-Regular-76... https://encore.scdn.co/fonts/SpotifyMixUI-Regular-76c92fb1a35c462f73429fa8865163eb.woff2 — 43.7 KiB — 0 ms — font-display: swaphttps://encore.scdn.co/fonts/SpotifyMixMono-Regular-134eeb986fc0f94a9f0acb9cedaeb584.woff2SpotifyMixMono-Regular-... https://encore.scdn.co/fonts/SpotifyMixMono-Regular-134eeb986fc0f94a9f0acb9cedaeb584.woff2 — 33.8 KiB — 0 ms — font-display: swaphttps://encore.scdn.co/fonts/SpotifyMixUITitleVariable-08bab3354d40f74e5177917b5ae80894.woff2SpotifyMixUITitleVariab... https://encore.scdn.co/fonts/SpotifyMixUITitleVariable-08bab3354d40f74e5177917b5ae80894.woff2 — 361.9 KiB — 0 ms — font-display: swaphttps://encore.scdn.co/fonts/SpotifyMixUI-Bold-09c45a3a0ce9d2971e62cb26e97760fb.woff2SpotifyMixUI-Bold-09c45... https://encore.scdn.co/fonts/SpotifyMixUI-Bold-09c45a3a0ce9d2971e62cb26e97760fb.woff2 — 46.7 KiB — 0 ms — font-display: swaphttps://encore.scdn.co/fonts/SpotifyMixUI-Regular-cc3b1de388efa4cbca6c75cebc24585e.woff2SpotifyMixUI-Regular-cc... https://encore.scdn.co/fonts/SpotifyMixUI-Regular-cc3b1de388efa4cbca6c75cebc24585e.woff2 — 35.0 KiB — 0 ms — font-display: swaphttps://encore.scdn.co/fonts/SpotifyMixUI-Bold-4264b799009b1db5c491778b1bc8e5b7.woff2SpotifyMixUI-Bold-4264b... https://encore.scdn.co/fonts/SpotifyMixUI-Bold-4264b799009b1db5c491778b1bc8e5b7.woff2 — 40.7 KiB — 0 ms — font-display: swaphttps://encore.scdn.co/fonts/SpotifyMixUITitleVariable-8769ccfde3379b7ebcadd9529b49d0cc.woff2SpotifyMixUITitleVariab... https://encore.scdn.co/fonts/SpotifyMixUITitleVariable-8769ccfde3379b7ebcadd9529b49d0cc.woff2 — 373.4 KiB — 0 ms — font-display: swap
SpotifyMixUI-Regular-76... woff2 swap
Size 44 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
SpotifyMixMono-Regular-... woff2 swap
Size 34 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
SpotifyMixUITitleVariab... woff2 swap
Size 362 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
SpotifyMixUI-Bold-09c45... woff2 swap
Size 47 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
SpotifyMixUI-Regular-cc... woff2 swap
Size 35 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
SpotifyMixUI-Bold-4264b... woff2 swap
Size 41 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
SpotifyMixUITitleVariab... woff2 swap
Size 373 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
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)

Fixing the unchecked items could save ~368 KB and ~736 ms

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+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Google Cloud

Network Waterfall
195 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
100% of JavaScript execution is third-party
First-party Third-party 4291ms · 1634KB · $57/mo
open.spotifycdn.com
Other
Costly
Execution 2518ms
Transfer 1022 KB
Unused 62%
Monthly Cost $33/mo
Unattributable
Other
Costly
Execution 553ms
Transfer 0 KB
Monthly Cost $7/mo
open.spotifycdn.com
Other
Costly
Execution 345ms
Transfer 93 KB
Unused 78%
Monthly Cost $5/mo
open.spotifycdn.com
Other
Costly
Execution 325ms
Transfer 230 KB
Unused 75%
Monthly Cost $4/mo
open.spotify.com
Other
Costly
Execution 244ms
Transfer 4 KB
Monthly Cost $3/mo
Google Tag Manager
Tag Manager
Optional
Execution 148ms
Transfer 158 KB
Unused 53%
Monthly Cost $2/mo
www.gstatic.com
Other
Optional
Execution 88ms
Transfer 0 KB
Unused 49%
Monthly Cost $1/mo
OneTrust
Consent
Essential
Execution 70ms
Transfer 128 KB
Unused 58%
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • open.spotifycdn.com adds 2518ms and costs ~$33/month
  • Unattributable adds 553ms and costs ~$7/month
  • open.spotifycdn.com adds 345ms and costs ~$5/month
  • open.spotifycdn.com adds 325ms and costs ~$4/month
  • open.spotify.com adds 244ms and costs ~$3/month

100% 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

open.spotifycdn.com takes 2518ms 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

62% of open.spotifycdn.com'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

Unattributable takes 553ms 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

open.spotifycdn.com takes 345ms 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

78% of open.spotifycdn.com'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

open.spotifycdn.com takes 325ms 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

75% of open.spotifycdn.com'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

open.spotify.com takes 244ms 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

53% of Google Tag Manager'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

58% of OneTrust'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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