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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
94
GRADE
A
FIX
1
REVIEW
3
PASS
11
INFO
2

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

Mobile Desktop
87
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.
96
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
83
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.

2.40 s

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

3.60 s

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.

0.003

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

2.40 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.

3.60 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 3 REVIEW 1 FIX
D
HTTP Caching
Action
no-store (uncacheable)
FIX
no-store (uncacheable)
Info::
Cache-Control: no-store prevents all caching
Intentional for dynamic content, but increases server load for every page view.
Got: no-store
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

no-store

DirectiveValueMeaning
no-store—Never cache this response
B
Third-Party Impact
45% third-party, 0 ms blocking
REVIEW
45% third-party, 0 ms blocking
Info::
Third-party code accounts for 45% of page weight (218.9 KiB of 485.4 KiB)
Info::
Third-party blocking time is low (0 ms)
55%
45%
First-party Third-party
B
JS Execution Cost
615ms total JS execution
REVIEW
615ms total JS execution
Warning::
Unattributable: 325ms CPU time
Warning::
https://www.ibiblio.org/: 289ms CPU time
Warning::
Third-party scripts: 615ms (100% of total)

Main Thread Breakdown

Other 43% Style & Layout 26% Script Evaluation 21% Parse HTML & CSS 5% Rendering 5%
ScriptTotalScriptingParse/CompileParty
Unattributable325ms75ms0ms3rd
https://www.ibiblio.org/289ms11ms2ms3rd
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
485 KB transferred, 22 requests
PASS
485 KB transferred, 22 requests
Info::
Page weighs 606 KB (485 KB transferred)
Info::
22 HTTP requests
Info::
Estimated 0.10 g CO2 per page load
485 KB / 2.4 MB budget
485 KB transferred
22 requests
0.10 g CO2 per page load
CSS 193.3 KiB 40%
Fonts 174.4 KiB 36%
Images 59.4 KiB 12%
JavaScript 27.8 KiB 6%
HTML 19.3 KiB 4%
Other 5.7 KiB 1%
Other 5.7 KiB 1%
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+
Image Optimization
3 images, 0 KB saveable
PASS
3 images, 0 KB saveable
Info::
All images are well-optimized
3 images 59 KB
0 oversized -0 KB
1 legacy format
0 missing dimensions CLS risk
A+
Font Loading
3 fonts (174 KB)
PASS
3 fonts (174 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

174 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 FCP 2.4 s LCP 3.6 sdata:font/woff2;base64,d09GMgABAAAAAOykABQAAAACdZgAAOwyAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGoUNG4LYfByR…woff2;base64,d09GMgABAA... data:font/woff2;base64,d09GMgABAAAAAOykABQAAAACdZgAAOwyAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGoUNG4LYfByR… — 59.2 KiB — 14 ms — font-display: swapdata:font/woff2;base64,d09GMgABAAAAAPq4ABUAAAACTIQAAPo7AAFmqAAAAAAAAAAAAAAAAAAAAAAAAAAAGokqG4Hrchya…woff2;base64,d09GMgABAA... data:font/woff2;base64,d09GMgABAAAAAPq4ABUAAAACTIQAAPo7AAFmqAAAAAAAAAAAAAAAAAAAAAAAAAAAGokqG4Hrchya… — 62.7 KiB — 17 ms — font-display: swaphttps://www.ibiblio.org/cms/wp-content/themes/twentytwentyfive/assets/fonts/manrope/Manrope-VariableFont_wght.woff2Manrope-VariableFont_wg... https://www.ibiblio.org/cms/wp-content/themes/twentytwentyfive/assets/fonts/manrope/Manrope-VariableFont_wght.woff2 — 52.5 KiB — 391 ms — font-display: swap
woff2;base64,d09GMgABAA... woff2 swap
Size 59 KB
Load time 14 ms
Start 760 ms
Risk FOUT — text flashes from fallback to web font
woff2;base64,d09GMgABAA... woff2 swap
Size 63 KB
Load time 17 ms
Start 761 ms
Risk FOUT — text flashes from fallback to web font
Manrope-VariableFont_wg... woff2 swap
Size 53 KB
Load time 391 ms
Start 1.8 s
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+
JS Bundles
7 scripts, 0 KB unused
PASS
7 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://ibiblio.org/.within.website/x/cmd/anubis/static/js/main.mjs?cacheBuster=1.25.06 KB—✓1st
https://ibiblio.org/.within.website/x/cmd/anubis/static/js/worker/sha256-webcrypto.mjs?cacheBuster=1.25.00 KB—✓1st
https://ibiblio.org/.within.website/x/cmd/anubis/static/js/worker/sha256-webcrypto.mjs?cacheBuster=1.25.00 KB—✓1st
https://www.ibiblio.org/cms/wp-includes/js/dist/script-modules/interactivity/index.min.js?ver=66c613f68580994bb00a15 KB—✓3rd
https://www.ibiblio.org/cms/wp-includes/js/dist/script-modules/block-library/navigation/view.min.js?ver=b0f909c3ec791c3832101 KB—✓3rd
blob:https://www.ibiblio.org/198d5ac3-8317-48d5-affa-29955da7e6b7-0 KB—✓3rd
https://www.ibiblio.org/cms/wp-includes/js/wp-emoji-release.min.js?ver=6.9.45 KB—✓3rd
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
22 resources · 485 KB · 0 KB savings available
PASS
22 resources · 485 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 485 KB
Warning::
11 third-party resources (45% of weight)
22 resources · 485.4 KiB · 11 third-party Within 1MB page-weight target
CSS 40% · 193.3 KiB
Font 36% · 174.4 KiB
Image 13% · 64.1 KiB
JavaScript 6% · 27.8 KiB
Document 4% · 20.2 KiB
Other 1% · 5.7 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
Network Waterfall
22 requests over 2265ms
INFO
0 ms 1.0 s 2.0 s 3.0 s FCP 2.4 s LCP 3.6 shttps://ibiblio.org// https://ibiblio.org/ — 200 — 2.8 KiB — 325 ms — http/1.1https://ibiblio.org/.within.website/x/xess/xess.min.css?cachebuster=1.25.0/.within.website/x/xess/xess.min.cs... https://ibiblio.org/.within.website/x/xess/xess.min.css?cachebuster=1.25.0 — 200 — 190.4 KiB — 420 ms — http/1.1https://ibiblio.org/.within.website/x/cmd/anubis/static/img/pensive.webp?cacheBuster=1.25.0/.within.website/x/cmd/anubis/stati... https://ibiblio.org/.within.website/x/cmd/anubis/static/img/pensive.webp?cacheBuster=1.25.0 — 200 — 28.4 KiB — 211 ms — http/1.1https://ibiblio.org/.within.website/x/cmd/anubis/static/img/happy.webp?cacheBuster=1.25.0/.within.website/x/cmd/anubis/stati... https://ibiblio.org/.within.website/x/cmd/anubis/static/img/happy.webp?cacheBuster=1.25.0 — 200 — 30.0 KiB — 316 ms — http/1.1https://ibiblio.org/.within.website/x/cmd/anubis/static/js/main.mjs?cacheBuster=1.25.0/.within.website/x/cmd/anubis/stati... https://ibiblio.org/.within.website/x/cmd/anubis/static/js/main.mjs?cacheBuster=1.25.0 — 200 — 5.8 KiB — 314 ms — http/1.1https://ibiblio.org/.within.website/x/cmd/anubis/static/locales/en.json/.within.website/x/cmd/anubis/stati... https://ibiblio.org/.within.website/x/cmd/anubis/static/locales/en.json — 200 — 5.7 KiB — 107 ms — http/1.1data:font/woff2;base64,d09GMgABAAAAAOykABQAAAACdZgAAOwyAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGoUNG4LYfByR…data:font/woff2;base64,d09GMgABAAAA... data:font/woff2;base64,d09GMgABAAAAAOykABQAAAACdZgAAOwyAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGoUNG4LYfByR… — 200 — 59.2 KiB — 14 ms — datadata:font/woff2;base64,d09GMgABAAAAAPq4ABUAAAACTIQAAPo7AAFmqAAAAAAAAAAAAAAAAAAAAAAAAAAAGokqG4Hrchya…data:font/woff2;base64,d09GMgABAAAA... data:font/woff2;base64,d09GMgABAAAAAPq4ABUAAAACTIQAAPo7AAFmqAAAAAAAAAAAAAAAAAAAAAAAAAAAGokqG4Hrchya… — 200 — 62.7 KiB — 17 ms — datahttps://ibiblio.org/.within.website/x/cmd/anubis/static/js/worker/sha256-webcrypto.mjs?cacheBuster=1.25.0/.within.website/x/cmd/anubis/stati... https://ibiblio.org/.within.website/x/cmd/anubis/static/js/worker/sha256-webcrypto.mjs?cacheBuster=1.25.0 — 200 — 187 B — 121 ms — http/1.1https://ibiblio.org/.within.website/x/cmd/anubis/static/js/worker/sha256-webcrypto.mjs?cacheBuster=1.25.0/.within.website/x/cmd/anubis/stati... https://ibiblio.org/.within.website/x/cmd/anubis/static/js/worker/sha256-webcrypto.mjs?cacheBuster=1.25.0 — 200 — 0 B — 120 ms — http/1.1https://ibiblio.org/favicon.ico/favicon.ico https://ibiblio.org/favicon.ico — 200 — 2.4 KiB — 107 ms — http/1.1https://ibiblio.org/.within.website/x/cmd/anubis/api/pass-challenge?id=019db1e9-b518-708d-bee1-db6c373ed071&response=0000d2c19ba3fbe4c855b1bf900b12c4790549210685adaf60def058aad66488&nonce=2530&redir=https%3A%2F%2Fibiblio.org%2F&elapsedTime=142/.within.website/x/cmd/anubis/api/p... https://ibiblio.org/.within.website/x/cmd/anubis/api/pass-challenge?id=019db1e9-b518-708d-bee1-db6c373ed071&response=0000d2c19ba3fbe4c855b1bf900b12c4790549210685adaf60def058aad66488&nonce=2530&redir=https%3A%2F%2Fibiblio.org%2F&elapsedTime=142 — 302 — 739 B — 106 ms — http/1.1https://ibiblio.org// https://ibiblio.org/ — 301 — 208 B — 129 ms — http/1.1https://www.ibiblio.org/www.ibiblio.org/ https://www.ibiblio.org/ — 200 — 16.5 KiB — 447 ms — http/1.1https://www.ibiblio.org/cms/wp-content/themes/twentytwentyfive-child/style.css?ver=1.0.3www.ibiblio.org/cms/wp-content/them... https://www.ibiblio.org/cms/wp-content/themes/twentytwentyfive-child/style.css?ver=1.0.3 — 200 — 3.0 KiB — 112 ms — http/1.1https://www.ibiblio.org/cms/wp-includes/js/dist/script-modules/interactivity/index.min.js?ver=66c613f68580994bb00awww.ibiblio.org/cms/wp-includes/js/... https://www.ibiblio.org/cms/wp-includes/js/dist/script-modules/interactivity/index.min.js?ver=66c613f68580994bb00a — 200 — 14.9 KiB — 224 ms — http/1.1https://www.ibiblio.org/cms/wp-content/uploads/2019/01/sm_ibiblio_trans.pngwww.ibiblio.org/cms/wp-content/uplo... https://www.ibiblio.org/cms/wp-content/uploads/2019/01/sm_ibiblio_trans.png — 200 — 975 B — 328 ms — http/1.1https://www.ibiblio.org/cms/wp-includes/js/dist/script-modules/block-library/navigation/view.min.js?ver=b0f909c3ec791c383210www.ibiblio.org/cms/wp-includes/js/... https://www.ibiblio.org/cms/wp-includes/js/dist/script-modules/block-library/navigation/view.min.js?ver=b0f909c3ec791c383210 — 200 — 1.4 KiB — 336 ms — http/1.1https://www.ibiblio.org/cms/wp-content/themes/twentytwentyfive/assets/fonts/manrope/Manrope-VariableFont_wght.woff2www.ibiblio.org/cms/wp-content/them... https://www.ibiblio.org/cms/wp-content/themes/twentytwentyfive/assets/fonts/manrope/Manrope-VariableFont_wght.woff2 — 200 — 52.5 KiB — 391 ms — http/1.1blob:https://www.ibiblio.org/198d5ac3-8317-48d5-affa-29955da7e6b7www.ibiblio.org/198d5ac3-8317-48d5-... blob:https://www.ibiblio.org/198d5ac3-8317-48d5-affa-29955da7e6b7 — 200 — -1 B — 40 ms — blobhttps://www.ibiblio.org/cms/wp-includes/js/wp-emoji-release.min.js?ver=6.9.4www.ibiblio.org/cms/wp-includes/js/... https://www.ibiblio.org/cms/wp-includes/js/wp-emoji-release.min.js?ver=6.9.4 — 200 — 5.5 KiB — 113 ms — http/1.1https://www.ibiblio.org/favicon.icowww.ibiblio.org/favicon.ico https://www.ibiblio.org/favicon.ico — 200 — 2.4 KiB — 108 ms — http/1.1
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
100% of JavaScript execution is third-party
First-party Third-party 615ms · 17KB · $8/mo
Unattributable
Other
Costly
Execution 325ms
Transfer 0 KB
Monthly Cost $4/mo
www.ibiblio.org
Other
Costly
Execution 289ms
Transfer 17 KB
Monthly Cost $4/mo

These scripts may cost more than they're worth

  • Unattributable adds 325ms and costs ~$4/month
  • www.ibiblio.org adds 289ms and costs ~$4/month

100% 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 325ms 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

www.ibiblio.org takes 289ms 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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