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Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
87
GRADE
B
FIX
2
REVIEW
4
PASS
8
INFO
2

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

Mobile Desktop
56
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
86
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.
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.

2.57 s

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

6.28 s

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

591 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.

4.54 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.

6.28 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
16
8 PASS 4 REVIEW 2 FIX
D
Third-Party Impact
Action
99% third-party, 0 ms blocking
FIX
99% third-party, 0 ms blocking
Warning::
Third-party code accounts for 99% of page weight (414.2 KiB of 417.6 KiB)
Info::
Third-party blocking time is low (0 ms)
99%
First-party Third-party
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.
Info::
Last-Modified header present

No Cache-Control header

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

C
Image Optimization
Action
19 images, 0 KB saveable
REVIEW
19 images, 0 KB saveable
Warning::
https://cdn.perl.org/perlweb/images/logo.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.perl.org/perlweb/images/icons/creative... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://cdn.perl.org/perlweb/images/icons/header_c... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
19 images 43 KB
0 oversized -0 KB
18 legacy format
3 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

C
JS Execution Cost
Action
1581ms total JS execution
REVIEW
1581ms total JS execution
Warning::
Unattributable: 550ms CPU time
Warning::
https://www.googletagmanager.com/gtag/js?id=G-H3V4...: 303ms CPU time
Info::
https://www.perl.org/: 233ms CPU time
Info::
https://cdn.perl.org/js/script.file-downloads.outb...: 194ms CPU time
Info::
https://www.googletagmanager.com/gtag/js?id=UA-505...: 194ms CPU time
Warning::
Third-party scripts: 1348ms (85% of total)

Main Thread Breakdown

Script Evaluation 46% Other 27% Style & Layout 13% Script Parsing & Compilation 10%
ScriptTotalScriptingParse/CompileParty
Unattributable550ms131ms0ms3rd
https://www.googletagmanager.com/gtag/js?id=G-H3V42907P1&cx=c&gtm=4e6460303ms225ms72ms3rd
https://www.perl.org/233ms134ms2ms1st
https://cdn.perl.org/js/script.file-downloads.outbound-links.js194ms29ms1ms3rd
https://www.googletagmanager.com/gtag/js?id=UA-50555-1194ms118ms70ms3rd
https://www.google-analytics.com/analytics.js106ms81ms9ms3rd
B
JS Bundles
6 scripts, 124 KB unused
REVIEW
6 scripts, 124 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-H3V4...: 62 KB unused (41%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.googletagmanager.com/gtag/js?id=UA-505...: 62 KB unused (53%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 124 KB
124 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-H3V42907P1&cx=c&gtm=4e6460153 KB62 KB (41%)✓3rd
https://www.googletagmanager.com/gtag/js?id=UA-50555-1116 KB62 KB (53%)✓3rd
https://cdn.perl.org/js/script.file-downloads.outbound-links.js2 KB—✓3rd
https://cdn.perl.org/perlweb/js/perlweb_bootstrap.min.js23 KB—✓3rd
https://www.google-analytics.com/analytics.js21 KB—✓3rd
https://www.google-analytics.com/plugins/ua/linkid.js1 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+
Page Weight Budget
418 KB transferred, 35 requests
PASS
418 KB transferred, 35 requests
Info::
Page weighs 1.1 MB (418 KB transferred)
Info::
35 HTTP requests
Info::
Estimated 0.09 g CO2 per page load
418 KB / 2.4 MB budget
418 KB transferred
35 requests
0.09 g CO2 per page load
JavaScript 316.0 KiB 76%
Images 42.8 KiB 10%
Fonts 41.2 KiB 10%
CSS 12.0 KiB 3%
HTML 3.4 KiB 1%
Other 904 B 0%
Other 808 B 0%
Other 556 B 0%
0 2.4 MB 4.9 MB
Under budget
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
3 fonts (41 KB)
PASS
3 fonts (41 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

41 KB total

Render-blocking

0

of 3

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 6.0 s FCP 2.6 s LCP 6.3 shttps://fonts.gstatic.com/s/lato/v25/S6uyw4BMUTPHjx4wXiWtFCc.woff2S6uyw4BMUTPHjx4wXiWtFCc... https://fonts.gstatic.com/s/lato/v25/S6uyw4BMUTPHjx4wXiWtFCc.woff2 — 13.7 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/lato/v25/S6u9w4BMUTPHh7USSwiPGQ3q5d0.woff2S6u9w4BMUTPHh7USSwiPGQ3... https://fonts.gstatic.com/s/lato/v25/S6u9w4BMUTPHh7USSwiPGQ3q5d0.woff2 — 13.6 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/lato/v25/S6u9w4BMUTPHh6UVSwiPGQ3q5d0.woff2S6u9w4BMUTPHh6UVSwiPGQ3... https://fonts.gstatic.com/s/lato/v25/S6u9w4BMUTPHh6UVSwiPGQ3q5d0.woff2 — 13.9 KiB — 0 ms — font-display: swap
S6uyw4BMUTPHjx4wXiWtFCc... woff2 swap
Size 14 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
S6u9w4BMUTPHh7USSwiPGQ3... woff2 swap
Size 14 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
S6u9w4BMUTPHh6UVSwiPGQ3... woff2 swap
Size 14 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
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
Network Waterfall
35 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
85% of JavaScript execution is third-party
First-party Third-party 1348ms · 292KB · $18/mo
Unattributable
Other
Costly
Execution 550ms
Transfer 0 KB
Monthly Cost $7/mo
Google Tag Manager
Tag Manager
Costly
Execution 303ms
Transfer 153 KB
Unused 41%
Monthly Cost $4/mo
cdn.perl.org
Other
Optional
Execution 194ms
Transfer 2 KB
Monthly Cost $3/mo
Google Tag Manager
Tag Manager
Optional
Execution 194ms
Transfer 116 KB
Unused 53%
Monthly Cost $3/mo
Google Analytics
Analytics
Optional
Execution 106ms
Transfer 21 KB
Monthly Cost $1/mo

These scripts may cost more than they're worth

  • Unattributable adds 550ms and costs ~$7/month
  • Google Tag Manager adds 303ms and costs ~$4/month

85% 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

Unattributable takes 550ms 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 303ms 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

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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