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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
77
GRADE
C
FIX
1
REVIEW
6
PASS
5
INFO
2

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

Mobile Desktop
98
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
96
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
73
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.

411 ms

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

986 ms

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

73 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.

1.06 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.

3.45 s

Page Load Progression

688 ms
1.4 s
2.1 s
2.8 s
3.4 s
4.1 s
4.8 s
5.5 s
Checks
14
5 PASS 6 REVIEW 1 FIX
F
JS Bundles
Action
42 scripts, 631 KB unused
FIX
42 scripts, 631 KB unused
Warning::
https://www.gstatic.com/recaptcha/releases/kUYUkUl...: 245 KB unused (68%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-CP29...: 65 KB unused (37%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-N63...: 62 KB unused (38%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=AW-662...: 53 KB unused (37%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cdn.cookielaw.org/scripttemplates/202304.1...: 52 KB unused (53%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 631 KB
631 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.gstatic.com/recaptcha/releases/kUYUkUlSyqkjTSMaN2w3RaOh/recaptcha__en.js363 KB245 KB (68%)✓3rd
https://www.googletagmanager.com/gtag/js?id=G-CP29SJK4E7&cx=c&gtm=4e6460177 KB65 KB (37%)✓3rd
https://www.googletagmanager.com/gtm.js?id=GTM-N633BZ8167 KB62 KB (38%)✓3rd
https://www.googletagmanager.com/gtag/js?id=AW-662873615&cx=c&gtm=4e6460146 KB53 KB (37%)✓3rd
https://cdn.cookielaw.org/scripttemplates/202304.1.0/otBannerSdk.js97 KB52 KB (53%)✓3rd
https://www.prefect.io/_next/static/chunks/0d62aab73d9e3e4a.js?dpl=dpl_28dSMm69PiuKWBPr3J369Wae9e1H43 KB38 KB (88%)✓1st
https://d-code.liadm.com/did-006l.min.js47 KB33 KB (71%)✓3rd
https://www.prefect.io/_next/static/chunks/fb74acd3f9a622b8.js?dpl=dpl_28dSMm69PiuKWBPr3J369Wae9e1H46 KB31 KB (69%)✓1st
https://www.prefect.io/_next/static/chunks/d68e5a1c93cc72e7.js?dpl=dpl_28dSMm69PiuKWBPr3J369Wae9e1H27 KB27 KB (100%)✓1st
https://www.prefect.io/_next/static/chunks/d6c3161eafdca609.js?dpl=dpl_28dSMm69PiuKWBPr3J369Wae9e1H70 KB24 KB (35%)✓1st

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

C
Page Weight Budget
Action
2.0 MB transferred, 156 requests
REVIEW
2.0 MB transferred, 156 requests
Info::
Page weighs 5.5 MB (2.0 MB transferred)
Warning::
JavaScript is 1.4 MB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 1.4 MB
Warning::
156 HTTP requests — consider bundling or reducing
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
Info::
Estimated 0.43 g CO2 per page load
2.0 MB / 2.4 MB budget
2.0 MB transferred
156 requests
0.43 g CO2 per page load
JavaScript 1.4 MiB 70%
Images 300.4 KiB 14%
Other 175.8 KiB 8%
Fonts 67.2 KiB 3%
CSS 50.5 KiB 2%
HTML 24.0 KiB 1%
Other 4.6 KiB 0%
Other 2.4 KiB 0%
Other 722 B 0%
Other 0 B 0%
0 2.4 MB 4.9 MB
Approaching limit

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

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

B
Third-Party Impact
57% third-party, 0 ms blocking
REVIEW
57% third-party, 0 ms blocking
Warning::
Third-party code accounts for 57% of page weight (1.2 MiB of 2.0 MiB)
Info::
Third-party blocking time is low (0 ms)
43%
57%
First-party Third-party
B
Image Optimization
38 images, 0 KB saveable
REVIEW
38 images, 0 KB saveable
Info::
All images are well-optimized
38 images 300 KB
0 oversized -0 KB
25 legacy format
0 missing dimensions CLS risk
C
JS Execution Cost
Action
1617ms total JS execution
REVIEW
1617ms total JS execution
Warning::
https://www.prefect.io/_next/static/chunks/d6c3161...: 272ms CPU time
Warning::
https://www.prefect.io/: 261ms CPU time
Info::
Unattributable: 223ms CPU time
Info::
https://www.gstatic.com/recaptcha/releases/kUYUkUl...: 186ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-CP29...: 144ms CPU time
Warning::
Third-party scripts: 1000ms (62% of total)

Main Thread Breakdown

Script Evaluation 54% Other 19% Script Parsing & Compilation 14% Style & Layout 8%
ScriptTotalScriptingParse/CompileParty
https://www.prefect.io/_next/static/chunks/d6c3161eafdca609.js?dpl=dpl_28dSMm69PiuKWBPr3J369Wae9e1H272ms204ms8ms1st
https://www.prefect.io/261ms8ms8ms1st
Unattributable223ms43ms0ms3rd
https://www.gstatic.com/recaptcha/releases/kUYUkUlSyqkjTSMaN2w3RaOh/recaptcha__en.js186ms77ms100ms3rd
https://www.googletagmanager.com/gtag/js?id=G-CP29SJK4E7&cx=c&gtm=4e6460144ms126ms17ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-N633BZ8120ms92ms20ms3rd
https://cdn.cookielaw.org/scripttemplates/202304.1.0/otBannerSdk.js104ms59ms33ms3rd
https://www.redditstatic.com/ads/pixel.js95ms83ms2ms3rd
https://www.prefect.io/_next/static/chunks/269dc890dd37ee5c.js?dpl=dpl_28dSMm69PiuKWBPr3J369Wae9e1H84ms54ms6ms1st
https://d-code.liadm.com/did-006l.min.js76ms51ms17ms3rd

Showing top 10 of 11 scripts

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

Green Hosting

No green hosting detected

B
HTTP Caching
public, max-age=0, must-revalidate
REVIEW
public, max-age=0, must-revalidate
Info::
Cache-Control header is set
Got: public, max-age=0, must-revalidate
Info::
ETag present — enables conditional (304) responses
Cache-Control

public, max-age=0, must-revalidate

DirectiveValueMeaning
public—Any cache may store this response
max-age0Cache for 0 seconds
must-revalidate—Must recheck with server after expiry
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
4 fonts (67 KB)
PASS
4 fonts (67 KB)
Info::
4 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

4

67 KB total

Render-blocking

0

of 4

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 411 ms LCP 986 mshttps://www.prefect.io/_next/static/media/caa3a2e1cccd8315-s.p.853070df.woff2caa3a2e1cccd8315-s.p.85... https://www.prefect.io/_next/static/media/caa3a2e1cccd8315-s.p.853070df.woff2 — 28.0 KiB — 0 ms — font-display: swaphttps://www.prefect.io/fonts/ArticulatCF-Regular.woff2ArticulatCF-Regular.woff2 https://www.prefect.io/fonts/ArticulatCF-Regular.woff2 — 16.2 KiB — 0 ms — font-display: swaphttps://www.prefect.io/fonts/ArticulatCF-DemiBold.woff2ArticulatCF-DemiBold.woff2 https://www.prefect.io/fonts/ArticulatCF-DemiBold.woff2 — 16.5 KiB — 0 ms — font-display: swaphttps://www.prefect.io/fonts/AeonikMonoTRIAL-Regular.woff2AeonikMonoTRIAL-Regular... https://www.prefect.io/fonts/AeonikMonoTRIAL-Regular.woff2 — 6.5 KiB — 0 ms — font-display: swap
caa3a2e1cccd8315-s.p.85... woff2 swap
Size 28 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
ArticulatCF-Regular.woff2 woff2 swap
Size 16 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
ArticulatCF-DemiBold.woff2 woff2 swap
Size 17 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
AeonikMonoTRIAL-Regular... woff2 swap
Size 7 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
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)
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
156 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
62% of JavaScript execution is third-party
First-party Third-party 1000ms · 1015KB · $17/mo
Unattributable
Other
Costly
Execution 223ms
Transfer 0 KB
Monthly Cost $4/mo
www.gstatic.com
Other
Optional
Execution 186ms
Transfer 363 KB
Unused 68%
Monthly Cost $3/mo
Google Tag Manager
Tag Manager
Optional
Execution 144ms
Transfer 177 KB
Unused 37%
Monthly Cost $2/mo
Google Tag Manager
Tag Manager
Optional
Execution 120ms
Transfer 167 KB
Unused 38%
Monthly Cost $2/mo
OneTrust
Consent
Essential
Execution 104ms
Transfer 97 KB
Unused 53%
Monthly Cost $2/mo
www.redditstatic.com
Other
Optional
Execution 95ms
Transfer 19 KB
Monthly Cost $2/mo
d-code.liadm.com
Other
Optional
Execution 76ms
Transfer 47 KB
Unused 71%
Monthly Cost $1/mo
Google Tag Manager
Tag Manager
Optional
Execution 51ms
Transfer 146 KB
Unused 37%
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • Unattributable adds 223ms and costs ~$4/month

62% 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

Unattributable takes 223ms 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

68% of www.gstatic.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

53% 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

71% of d-code.liadm.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

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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