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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
90
GRADE
A
FIX
0
REVIEW
4
PASS
11
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.
100
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.
85
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.

1.81 s

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

1.96 s

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

96 ms

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

0.030

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

1.81 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.

5.36 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
17
11 PASS 4 REVIEW
C
Image Optimization
Action
11 images, 0 KB saveable
REVIEW
11 images, 0 KB saveable
Warning::
https://metacpan.org/static/images/metacpan-logo.s... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://metacpan.org/static/images/sponsors/datado... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://metacpan.org/static/images/sponsors/elasti... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://metacpan.org/static/images/sponsors/fastly... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://metacpan.org/static/images/sponsors/geocod... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://metacpan.org/static/images/sponsors/iban-l... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://metacpan.org/static/images/sponsors/bytema... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://metacpan.org/static/images/sponsors/deriv.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://metacpan.org/static/images/sponsors/liquid... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://metacpan.org/static/images/sponsors/open-c... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://metacpan.org/static/images/sponsors/perl-o... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
11 images 89 KB
0 oversized -0 KB
11 legacy format
11 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

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 Execution Cost
865ms total JS execution
REVIEW
865ms total JS execution
Warning::
Unattributable: 250ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=G-E82Q...: 248ms CPU time
Info::
https://metacpan.org/: 197ms CPU time
Info::
https://metacpan.org/assets/main-7ONN3P5A.js: 170ms CPU time
Warning::
Third-party scripts: 498ms (58% of total)

Main Thread Breakdown

Script Evaluation 42% Other 36% Style & Layout 10% Parse HTML & CSS 5% Script Parsing & Compilation 4%
ScriptTotalScriptingParse/CompileParty
Unattributable250ms9ms0ms3rd
https://www.googletagmanager.com/gtag/js?id=G-E82Q2V8LVD248ms210ms36ms3rd
https://metacpan.org/197ms8ms0ms1st
https://metacpan.org/assets/main-7ONN3P5A.js170ms152ms1ms1st
C
JS Bundles
Action
2 scripts, 162 KB unused
REVIEW
2 scripts, 162 KB unused
Warning::
https://metacpan.org/assets/main-7ONN3P5A.js: 97 KB unused (74%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=G-E82Q...: 65 KB unused (41%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 162 KB
162 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://metacpan.org/assets/main-7ONN3P5A.js131 KB97 KB (74%)✓1st
https://www.googletagmanager.com/gtag/js?id=G-E82Q2V8LVD159 KB65 KB (41%)✓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
Page Weight Budget
720 KB transferred, 23 requests
PASS
720 KB transferred, 23 requests
Info::
Page weighs 1.6 MB (720 KB transferred)
Info::
Fonts are 271 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 271 KB
Info::
23 HTTP requests
Info::
Estimated 0.15 g CO2 per page load
720 KB / 2.4 MB budget
720 KB transferred
23 requests
0.15 g CO2 per page load
JavaScript 289.9 KiB 40%
Fonts 271.0 KiB 38%
Images 89.2 KiB 12%
CSS 60.4 KiB 8%
Other 4.1 KiB 1%
HTML 3.5 KiB 0%
Other 2.2 KiB 0%
0 2.4 MB 4.9 MB
Under 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

A
Third-Party Impact
22% third-party, 0 ms blocking
PASS
22% third-party, 0 ms blocking
Info::
Third-party code accounts for 22% of page weight (161.4 KiB of 720.4 KiB)
Info::
Third-party blocking time is low (0 ms)
78%
22%
First-party Third-party
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
2 fonts (271 KB)
PASS
2 fonts (271 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

271 KB total

Render-blocking

0

of 2

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 1.8 s LCP 2.0 shttps://metacpan.org/assets/fa-solid-900-5ZUYHGA7.woff2fa-solid-900-5ZUYHGA7.w... https://metacpan.org/assets/fa-solid-900-5ZUYHGA7.woff2 — 154.8 KiB — 19 ms — font-display: swaphttps://metacpan.org/assets/fa-brands-400-Q3XCMWHQ.woff2fa-brands-400-Q3XCMWHQ.... https://metacpan.org/assets/fa-brands-400-Q3XCMWHQ.woff2 — 116.2 KiB — 22 ms — font-display: swap
fa-solid-900-5ZUYHGA7.w... woff2 swap
Size 155 KB
Load time 19 ms
Start 86 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
fa-brands-400-Q3XCMWHQ.... woff2 swap
Size 116 KB
Load time 22 ms
Start 86 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 ~135 KB and ~270 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
1 hints, 0 missing preconnects
PASS
1 hints, 0 missing preconnects
Info::
Page uses 1 resource hint(s)

Current Resource Hints

preconnect
—
preload
1
dns-prefetch
—
prefetch
—

1 resource hints configured

A+
Page Weight Inventory
23 resources · 720 KB · 162 KB savings available
PASS
23 resources · 720 KB · 162 KB savings available
Info::
Within 1MB page-weight target
Got: 720 KB
Info::
~162 KB of savings available
Info::
4 third-party resources (22% of weight)
23 resources · 720.4 KiB · 4 third-party Within 1MB page-weight target
JavaScript 40% · 289.9 KiB
Font 38% · 271.0 KiB
Image 13% · 93.2 KiB
CSS 8% · 60.4 KiB
Document 0% · 3.5 KiB
Other 0% · 2.4 KiB

~161.6 KiB of savings available

Remove unused JavaScript: 161.6 KiB
A+
Render-Blocking Resources
No render-blocking resources detected
PASS
No render-blocking resources detected
Info::
No render-blocking resources detected in <head>
A+
Third-Party Resources
No third-party resources detected
PASS
No third-party resources detected
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::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

max-age=3600

DirectiveValueMeaning
max-age3600Cache for 1 hour
Effective TTL: 3600 seconds
Network Waterfall
23 requests over 461ms
INFO
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 1.8 s LCP 2.0 shttps://metacpan.org// https://metacpan.org/ — 200 — 3.5 KiB — 13 ms — h2https://metacpan.org/account/login_status/account/login_status https://metacpan.org/account/login_status — 200 — 171 B — 3 ms — h2https://metacpan.org/assets/style-3JV6V6B4.css/assets/style-3JV6V6B4.css https://metacpan.org/assets/style-3JV6V6B4.css — 200 — 60.4 KiB — 9 ms — h2https://metacpan.org/assets/main-7ONN3P5A.js/assets/main-7ONN3P5A.js https://metacpan.org/assets/main-7ONN3P5A.js — 200 — 130.8 KiB — 12 ms — h2https://metacpan.org/static/images/metacpan-logo.svg/static/images/metacpan-logo.svg https://metacpan.org/static/images/metacpan-logo.svg — 200 — 2.1 KiB — 7 ms — h2https://metacpan.org/static/images/metacpan-logo.svg/static/images/metacpan-logo.svg https://metacpan.org/static/images/metacpan-logo.svg — 200 — 0 B — 6 ms — h2https://metacpan.org/static/images/sponsors/bytemark_logo.svg/static/images/sponsors/bytemark_lo... https://metacpan.org/static/images/sponsors/bytemark_logo.svg — 200 — 6.5 KiB — 16 ms — h2https://metacpan.org/static/images/sponsors/datadog.svg/static/images/sponsors/datadog.svg https://metacpan.org/static/images/sponsors/datadog.svg — 200 — 2.7 KiB — 27 ms — h2https://metacpan.org/static/images/sponsors/deriv.svg/static/images/sponsors/deriv.svg https://metacpan.org/static/images/sponsors/deriv.svg — 200 — 1.6 KiB — 16 ms — h2https://metacpan.org/static/images/sponsors/elastic.svg/static/images/sponsors/elastic.svg https://metacpan.org/static/images/sponsors/elastic.svg — 200 — 1.8 KiB — 15 ms — h2https://metacpan.org/static/images/sponsors/fastly_logo.svg/static/images/sponsors/fastly_logo... https://metacpan.org/static/images/sponsors/fastly_logo.svg — 200 — 1.9 KiB — 24 ms — h2https://metacpan.org/static/images/sponsors/geocodelogo.svg/static/images/sponsors/geocodelogo... https://metacpan.org/static/images/sponsors/geocodelogo.svg — 200 — 2.1 KiB — 18 ms — h2https://metacpan.org/static/images/sponsors/iban-logo.png/static/images/sponsors/iban-logo.p... https://metacpan.org/static/images/sponsors/iban-logo.png — 200 — 37.8 KiB — 14 ms — h2https://metacpan.org/static/images/sponsors/liquidweb_logo.png/static/images/sponsors/liquidweb_l... https://metacpan.org/static/images/sponsors/liquidweb_logo.png — 200 — 25.9 KiB — 25 ms — h2https://metacpan.org/static/images/sponsors/open-cage.svg/static/images/sponsors/open-cage.s... https://metacpan.org/static/images/sponsors/open-cage.svg — 200 — 3.5 KiB — 25 ms — h2https://metacpan.org/static/images/sponsors/perl-onion.svg/static/images/sponsors/perl-onion.... https://metacpan.org/static/images/sponsors/perl-onion.svg — 200 — 3.4 KiB — 17 ms — h2https://metacpan.org/assets/fa-solid-900-5ZUYHGA7.woff2/assets/fa-solid-900-5ZUYHGA7.woff2 https://metacpan.org/assets/fa-solid-900-5ZUYHGA7.woff2 — 200 — 154.8 KiB — 19 ms — h2https://metacpan.org/assets/fa-brands-400-Q3XCMWHQ.woff2/assets/fa-brands-400-Q3XCMWHQ.woff... https://metacpan.org/assets/fa-brands-400-Q3XCMWHQ.woff2 — 200 — 116.2 KiB — 22 ms — h2https://www.googletagmanager.com/gtag/js?id=G-E82Q2V8LVDwww.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-E82Q2V8LVD — 200 — 159.2 KiB — 177 ms — h2https://perl-ads.perlhacks.com/perl-ads.jsonperl-ads.perlhacks.com/perl-ads.jso... https://perl-ads.perlhacks.com/perl-ads.json — 200 — 1.6 KiB — 205 ms — h2https://region1.google-analytics.com/g/collect?v=2&tid=G-E82Q2V8LVD&gtm=45je64k1h1v896706794za200zd896706794&_p=1776900152814&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&_eu=EA&are=1&cid=1249705384.1776900153&frm=0&ir=1&pscdl=noapi&rcb=15&sr=412x823&uaa=&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=moto%20g%20power%20(2022)&uamb=1&uap=Android&uapv=11.0&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938465~115938469~117266401~117512543&sid=1776900153&sct=1&seg=0&dl=https%3A%2F%2Fmetacpan.org%2F&dt=Search%20the%20CPAN%20-%20metacpan.org&_tu=QA&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=345region1.google-analytics.com/g/coll... https://region1.google-analytics.com/g/collect?v=2&tid=G-E82Q2V8LVD&gtm=45je64k1h1v896706794za200zd896706794&_p=1776900152814&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&_eu=EA&are=1&cid=1249705384.1776900153&frm=0&ir=1&pscdl=noapi&rcb=15&sr=412x823&uaa=&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=moto%20g%20power%20(2022)&uamb=1&uap=Android&uapv=11.0&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938465~115938469~117266401~117512543&sid=1776900153&sct=1&seg=0&dl=https%3A%2F%2Fmetacpan.org%2F&dt=Search%20the%20CPAN%20-%20metacpan.org&_tu=QA&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=345 — 204 — 48 B — 116 ms — h2https://region1.google-analytics.com/g/collect?v=2&tid=G-6B2JCQSHJE&gtm=45je64k1h1v896706794za200zd896706794&_p=1776900152814&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&_eu=EA&are=1&cid=1249705384.1776900153&frm=0&ir=1&pscdl=noapi&rcb=15&sr=412x823&uaa=&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=moto%20g%20power%20(2022)&uamb=1&uap=Android&uapv=11.0&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938465~115938469~117266401~117512543&sid=1776900153&sct=1&seg=0&dl=https%3A%2F%2Fmetacpan.org%2F&dt=Search%20the%20CPAN%20-%20metacpan.org&_tu=QA&en=page_view&_fv=1&_ss=1&_ee=1&tfd=351region1.google-analytics.com/g/coll... https://region1.google-analytics.com/g/collect?v=2&tid=G-6B2JCQSHJE&gtm=45je64k1h1v896706794za200zd896706794&_p=1776900152814&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&_eu=EA&are=1&cid=1249705384.1776900153&frm=0&ir=1&pscdl=noapi&rcb=15&sr=412x823&uaa=&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=moto%20g%20power%20(2022)&uamb=1&uap=Android&uapv=11.0&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938465~115938469~117266401~117512543&sid=1776900153&sct=1&seg=0&dl=https%3A%2F%2Fmetacpan.org%2F&dt=Search%20the%20CPAN%20-%20metacpan.org&_tu=QA&en=page_view&_fv=1&_ss=1&_ee=1&tfd=351 — 204 — 546 B — 110 ms — h2https://metacpan.org/static/icons/favicon.ico/static/icons/favicon.ico https://metacpan.org/static/icons/favicon.ico — 200 — 4.0 KiB — 3 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
58% of JavaScript execution is third-party
First-party Third-party 498ms · 159KB · $7/mo
Unattributable
Other
Costly
Execution 250ms
Transfer 0 KB
Monthly Cost $3/mo
Google Tag Manager
Tag Manager
Costly
Execution 248ms
Transfer 159 KB
Unused 41%
Monthly Cost $3/mo

These scripts may cost more than they're worth

  • Unattributable adds 250ms and costs ~$3/month
  • Google Tag Manager adds 248ms and costs ~$3/month

58% 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 250ms 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

Google Tag Manager takes 248ms 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

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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