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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
90
GRADE
A
FIX
0
REVIEW
3
PASS
10
INFO
2

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

Mobile Desktop
100
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.

536 ms

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

600 ms

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.

0.031

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

536 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.

602 ms

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
15
10 PASS 3 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/deriv.... 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/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/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/bytema... 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/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

C
JS Bundles
Action
2 scripts, 160 KB unused
REVIEW
2 scripts, 160 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...: 63 KB unused (40%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 160 KB
160 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 KB63 KB (40%)✓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 290.2 KiB 40%
Fonts 271.2 KiB 38%
Images 88.9 KiB 12%
CSS 60.1 KiB 8%
Other 4.2 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+
JS Execution Cost
192ms total JS execution
PASS
192ms total JS execution
Info::
https://www.googletagmanager.com/gtag/js?id=G-E82Q...: 76ms CPU time
Info::
Unattributable: 59ms CPU time
Info::
https://metacpan.org/: 57ms CPU time
Warning::
Third-party scripts: 135ms (71% of total)

Main Thread Breakdown

Script Evaluation 45% Other 33% Style & Layout 9% Parse HTML & CSS 5% Script Parsing & Compilation 4%
ScriptTotalScriptingParse/CompileParty
https://www.googletagmanager.com/gtag/js?id=G-E82Q2V8LVD76ms65ms10ms3rd
Unattributable59ms3ms0ms3rd
https://metacpan.org/57ms2ms0ms1st
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 FCP 536 ms LCP 600 mshttps://metacpan.org/assets/fa-solid-900-5ZUYHGA7.woff2fa-solid-900-5ZUYHGA7.w... https://metacpan.org/assets/fa-solid-900-5ZUYHGA7.woff2 — 154.8 KiB — 16 ms — font-display: swaphttps://metacpan.org/assets/fa-brands-400-Q3XCMWHQ.woff2fa-brands-400-Q3XCMWHQ.... https://metacpan.org/assets/fa-brands-400-Q3XCMWHQ.woff2 — 116.4 KiB — 25 ms — font-display: swap
fa-solid-900-5ZUYHGA7.w... woff2 swap
Size 155 KB
Load time 16 ms
Start 87 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 25 ms
Start 87 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 ~136 KB and ~272 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+
Page Weight Inventory
23 resources · 720 KB · 160 KB savings available
PASS
23 resources · 720 KB · 160 KB savings available
Info::
Within 1MB page-weight target
Got: 720 KB
Info::
~160 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% · 290.2 KiB
Font 38% · 271.2 KiB
Image 13% · 92.9 KiB
CSS 8% · 60.1 KiB
Document 0% · 3.5 KiB
Other 0% · 2.4 KiB

~159.7 KiB of savings available

Remove unused JavaScript: 159.7 KiB
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 433ms
INFO
0 ms 200 ms 400 ms 600 ms FCP 536 ms LCP 600 mshttps://metacpan.org// https://metacpan.org/ — 200 — 3.5 KiB — 7 ms — h2https://metacpan.org/account/login_status/account/login_status https://metacpan.org/account/login_status — 200 — 171 B — 2 ms — h2https://metacpan.org/assets/style-3JV6V6B4.css/assets/style-3JV6V6B4.css https://metacpan.org/assets/style-3JV6V6B4.css — 200 — 60.1 KiB — 10 ms — h2https://metacpan.org/assets/main-7ONN3P5A.js/assets/main-7ONN3P5A.js https://metacpan.org/assets/main-7ONN3P5A.js — 200 — 131.1 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 — 10 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 — 3 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 — 6.2 KiB — 19 ms — h2https://metacpan.org/static/images/sponsors/datadog.svg/static/images/sponsors/datadog.svg https://metacpan.org/static/images/sponsors/datadog.svg — 200 — 2.8 KiB — 24 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 — 18 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 — 18 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 — 25 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 — 17 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 — 20 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 — 22 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 — 24 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 — 25 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 — 16 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 — 116.4 KiB — 25 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 — 172 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 — 7 ms — h2https://region1.google-analytics.com/g/collect?v=2&tid=G-E82Q2V8LVD&gtm=45je64k1v896706794za200zd896706794&_p=1776900164882&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&_eu=EA&are=1&cid=2017640653.1776900165&frm=0&ir=1&pscdl=noapi&rcb=7&sr=800x600&uaa=x86&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115938465~115938469~117266401~117384406~117512542&sid=1776900165&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=349region1.google-analytics.com/g/coll... https://region1.google-analytics.com/g/collect?v=2&tid=G-E82Q2V8LVD&gtm=45je64k1v896706794za200zd896706794&_p=1776900164882&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&_eu=EA&are=1&cid=2017640653.1776900165&frm=0&ir=1&pscdl=noapi&rcb=7&sr=800x600&uaa=x86&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115938465~115938469~117266401~117384406~117512542&sid=1776900165&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=349 — 204 — 546 B — 83 ms — h2https://region1.google-analytics.com/g/collect?v=2&tid=G-6B2JCQSHJE&gtm=45je64k1v896706794za200zd896706794&_p=1776900164882&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&_eu=EA&are=1&cid=2017640653.1776900165&frm=0&ir=1&pscdl=noapi&rcb=7&sr=800x600&uaa=x86&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115938465~115938469~117266401~117384406~117512542&sid=1776900165&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=356region1.google-analytics.com/g/coll... https://region1.google-analytics.com/g/collect?v=2&tid=G-6B2JCQSHJE&gtm=45je64k1v896706794za200zd896706794&_p=1776900164882&gcd=13l3l3l2l1l1&npa=1&dma_cps=a&dma=1&_eu=EA&are=1&cid=2017640653.1776900165&frm=0&ir=1&pscdl=noapi&rcb=7&sr=800x600&uaa=x86&uab=64&uafvl=Chromium%3B147.0.7727.101%7CNot.A%252FBrand%3B8.0.0.0&uam=&uamb=0&uap=macOS&uapv=10.15.7&uaw=0&ul=en-us&_s=1&tag_exp=0~115938465~115938469~117266401~117384406~117512542&sid=1776900165&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=356 — 204 — 48 B — 77 ms — h2https://metacpan.org/static/icons/favicon.ico/static/icons/favicon.ico https://metacpan.org/static/icons/favicon.ico — 200 — 4.0 KiB — 4 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
71% of JavaScript execution is third-party
First-party Third-party 135ms · 159KB · $2/mo
Google Tag Manager
Tag Manager
Optional
Execution 76ms
Transfer 159 KB
Unused 40%
Monthly Cost $1/mo
Unattributable
Other
Optional
Execution 59ms
Transfer 0 KB
Monthly Cost $1/mo

71% 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

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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