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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
86
GRADE
B
FIX
2
REVIEW
3
PASS
7
INFO
2

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

Mobile Desktop
99
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
93
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.

556 ms

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

862 ms

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

5 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.

556 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.

1.93 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
7 PASS 3 REVIEW 2 FIX
F
Page Weight Budget
Action
3.4 MB transferred, 71 requests
FIX
3.4 MB transferred, 71 requests
Warning::
Page weighs 9.6 MB (3.4 MB transferred)
Info::
Fonts are 518 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 518 KB
Info::
71 HTTP requests
Info::
Estimated 0.72 g CO2 per page load
3.4 MB / 2.4 MB budget
3.4 MB transferred
71 requests
0.72 g CO2 per page load
Other 2.3 MiB 66%
Fonts 518.2 KiB 15%
JavaScript 490.4 KiB 14%
Images 67.6 KiB 2%
Other 60.1 KiB 2%
CSS 28.7 KiB 1%
HTML 16.4 KiB 0%
Other 460 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Over budget

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

D
Third-Party Impact
Action
91% third-party, 0 ms blocking
FIX
91% third-party, 0 ms blocking
Warning::
Third-party code accounts for 91% of page weight (3.1 MiB of 3.4 MiB)
Info::
Third-party blocking time is low (0 ms)
91%
First-party Third-party
C
Image Optimization
Action
9 images, 0 KB saveable
REVIEW
9 images, 0 KB saveable
Warning::
https://dart.dev/assets/img/logo/dart-192.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://dart.dev/assets/dash/svg/1-1-async-await.s... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://dart.dev/assets/img/logo/logo-white-text.s... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://dart.dev/assets/dash/2x/supported-by-googl... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://dart.dev/assets/dash/svg/3-1-aot-compile.s... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://dart.dev/assets/dash/svg/2-1-hot-reload-it... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
9 images 68 KB
0 oversized -0 KB
9 legacy format
6 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

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

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

B
JS Bundles
12 scripts, 135 KB unused
REVIEW
12 scripts, 135 KB unused
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-5VS...: 73 KB unused (55%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-X5H2...: 62 KB unused (41%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 135 KB
135 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtm.js?id=GTM-5VSZM5J132 KB73 KB (55%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-X5H2ZXSYH5&cx=c&_slc=1150 KB62 KB (41%)✓3rd
https://cdn.jsdelivr.net/npm/@justinribeiro/lite-youtube@1.8.2/lite-youtube.js4 KB—✓3rd
https://dart.dev/main.client.dart.js1 KB—✓1st
https://www.google-analytics.com/analytics.js21 KB—✓3rd
https://dart.dev/main.client.mjs5 KB—✓1st
https://dartpad.dev/codemirror/codemirror.js105 KB—✓3rd
https://dartpad.dev/ga.js1 KB—✓3rd
https://www.gstatic.com/glue/cookienotificationbar/cookienotificationbar.min.js27 KB—✓3rd
https://www.google-analytics.com/analytics.js21 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

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

Green Hosting

No green hosting detected

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
269ms total JS execution
PASS
269ms total JS execution
Info::
https://dart.dev/: 108ms CPU time
Info::
Unattributable: 98ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-X5H2...: 63ms CPU time
Warning::
Third-party scripts: 161ms (60% of total)

Main Thread Breakdown

Script Evaluation 37% Other 30% Style & Layout 19% Script Parsing & Compilation 5% Parse HTML & CSS 4% Garbage Collection 3%
ScriptTotalScriptingParse/CompileParty
https://dart.dev/108ms4ms1ms1st
Unattributable98ms2ms0ms3rd
https://www.googletagmanager.com/gtag/js?id=G-X5H2ZXSYH5&cx=c&_slc=163ms54ms9ms3rd
A+
Font Loading
9 fonts (681 KB)
PASS
9 fonts (681 KB)
Info::
9 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

9

681 KB total

Render-blocking

0

of 9

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 556 ms LCP 862 mshttps://fonts.gstatic.com/s/googlesans/v67/4UasrENHsxJlGDuGo1OIlJfC6l_24rlCK1Yo_Iqcsih3SAyH6cAwhX9RPjIUvbQoi-E.woff24UasrENHsxJlGDuGo1OIlJf... https://fonts.gstatic.com/s/googlesans/v67/4UasrENHsxJlGDuGo1OIlJfC6l_24rlCK1Yo_Iqcsih3SAyH6cAwhX9RPjIUvbQoi-E.woff2 — 35.3 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/materialsymbolsoutlined/v323/kJF4BvYX7BgnkSrUwT8OhrdQw4oELdPIeeII9v6oDMzBwG-RpA6RzaxHMPdY40KH8nGzv3fzfVJU22ZZLsYEpzC_1ver5Y0J1Llf.woff2kJF4BvYX7BgnkSrUwT8Ohrd... https://fonts.gstatic.com/s/materialsymbolsoutlined/v323/kJF4BvYX7BgnkSrUwT8OhrdQw4oELdPIeeII9v6oDMzBwG-RpA6RzaxHMPdY40KH8nGzv3fzfVJU22ZZLsYEpzC_1ver5Y0J1Llf.woff2 — 439.8 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/googlesanstext/v25/5aUu9-KzpRiLCAt4Unrc-xIKmCU5qEp2i0VBuxM.woff25aUu9-KzpRiLCAt4Unrc-xI... https://fonts.gstatic.com/s/googlesanstext/v25/5aUu9-KzpRiLCAt4Unrc-xIKmCU5qEp2i0VBuxM.woff2 — 21.6 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/roboto/v51/KFOMCnqEu92Fr1ME7kSn66aGLdTylUAMQXC89YmC2DPNWubEbVmUiAo.woff2KFOMCnqEu92Fr1ME7kSn66a... https://fonts.gstatic.com/s/roboto/v51/KFOMCnqEu92Fr1ME7kSn66aGLdTylUAMQXC89YmC2DPNWubEbVmUiAo.woff2 — 21.4 KiB — 0 ms — font-display: swaphttps://dartpad.dev/assets/fonts/MaterialIcons-Regular.otfMaterialIcons-Regular.otf https://dartpad.dev/assets/fonts/MaterialIcons-Regular.otf — 5.2 KiB — 0 ms — font-display: swaphttps://dartpad.dev/assets/assets/RobotoMono-Regular.ttfRobotoMono-Regular.ttf https://dartpad.dev/assets/assets/RobotoMono-Regular.ttf — 47.4 KiB — 0 ms — font-display: swaphttps://dartpad.dev/assets/assets/RobotoMono-Bold.ttfRobotoMono-Bold.ttf https://dartpad.dev/assets/assets/RobotoMono-Bold.ttf — 47.9 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/roboto/v32/KFOmCnqEu92Fr1Me4GZLCzYlKw.woff2KFOmCnqEu92Fr1Me4GZLCzY... https://fonts.gstatic.com/s/roboto/v32/KFOmCnqEu92Fr1Me4GZLCzYlKw.woff2 — 62.0 KiB — 0 ms — font-display: swaphttps://dartpad.dev/assets/assets/RobotoMono-Regular.ttfRobotoMono-Regular.ttf https://dartpad.dev/assets/assets/RobotoMono-Regular.ttf — 0 B — 0 ms — font-display: swap
4UasrENHsxJlGDuGo1OIlJf... woff2 swap
Size 35 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
kJF4BvYX7BgnkSrUwT8Ohrd... woff2 swap
Size 440 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
5aUu9-KzpRiLCAt4Unrc-xI... woff2 swap
Size 22 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
KFOMCnqEu92Fr1ME7kSn66a... woff2 swap
Size 21 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
MaterialIcons-Regular.otf otf swap
Size 5 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
RobotoMono-Regular.ttf ttf swap
Size 47 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
RobotoMono-Bold.ttf ttf swap
Size 48 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
KFOmCnqEu92Fr1Me4GZLCzY... woff2 swap
Size 62 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
RobotoMono-Regular.ttf ttf swap
Size 0 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
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 ~250 KB and ~500 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+
HTTP Caching
max-age=3600 (1 hour)
PASS
max-age=3600 (1 hour)
Info::
Cache-Control header is set
Got: max-age=3600
Info::
Effective TTL: 1 hour (max-age=3600)
Info::
ETag present — enables conditional (304) responses
Info::
Last-Modified header present
Cache-Control

max-age=3600

DirectiveValueMeaning
max-age3600Cache for 1 hour
Effective TTL: 3600 seconds
Network Waterfall
71 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
60% of JavaScript execution is third-party
First-party Third-party 161ms · 150KB · €2/mo
Unattributable
Other
Optional
Execution 98ms
Transfer 0 KB
Monthly Cost €1/mo
Google Tag Manager
Tag Manager
Optional
Execution 63ms
Transfer 150 KB
Unused 41%
Monthly Cost €1/mo

60% 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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