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Performance

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

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

Mobile Desktop
99
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.
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.

772 ms

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

813 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.

0.017

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

772 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.

813 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
11 PASS 1 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
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
431 KB transferred, 21 requests
PASS
431 KB transferred, 21 requests
Info::
Page weighs 551 KB (431 KB transferred)
Info::
21 HTTP requests
Info::
Estimated 0.09 g CO2 per page load
431 KB / 2.4 MB budget
431 KB transferred
21 requests
0.09 g CO2 per page load
CSS 193.3 KiB 45%
Fonts 121.8 KiB 28%
Images 59.4 KiB 14%
JavaScript 27.8 KiB 6%
HTML 19.3 KiB 4%
Other 5.7 KiB 1%
Other 3.3 KiB 1%
0 2.4 MB 4.9 MB
Under budget
A
Third-Party Impact
38% third-party, 0 ms blocking
PASS
38% third-party, 0 ms blocking
Info::
Third-party code accounts for 38% of page weight (164.0 KiB of 430.5 KiB)
Info::
Third-party blocking time is low (0 ms)
62%
38%
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+
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+
JS Execution Cost
253ms total JS execution
PASS
253ms total JS execution
Info::
https://www.ibiblio.org/: 177ms CPU time
Info::
Unattributable: 77ms CPU time
Warning::
Third-party scripts: 253ms (100% of total)

Main Thread Breakdown

Other 51% Style & Layout 26% Script Evaluation 13% Rendering 7%
ScriptTotalScriptingParse/CompileParty
https://www.ibiblio.org/177ms4ms1ms3rd
Unattributable77ms13ms0ms3rd
A+
Font Loading
3 fonts (122 KB)
PASS
3 fonts (122 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

122 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 500 ms 1.0 s FCP 772 ms LCP 813 msdata:font/woff2;base64,d09GMgABAAAAAOykABQAAAACdZgAAOwyAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGoUNG4LYfByR…woff2;base64,d09GMgABAA... data:font/woff2;base64,d09GMgABAAAAAOykABQAAAACdZgAAOwyAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGoUNG4LYfByR… — 59.2 KiB — 20 ms — font-display: swapdata:font/woff2;base64,d09GMgABAAAAAPq4ABUAAAACTIQAAPo7AAFmqAAAAAAAAAAAAAAAAAAAAAAAAAAAGokqG4Hrchya…woff2;base64,d09GMgABAA... data:font/woff2;base64,d09GMgABAAAAAPq4ABUAAAACTIQAAPo7AAFmqAAAAAAAAAAAAAAAAAAAAAAAAAAAGokqG4Hrchya… — 62.7 KiB — 24 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 — 0 B — -2826 ms — font-display: swap
woff2;base64,d09GMgABAA... woff2 swap
Size 59 KB
Load time 20 ms
Start 752 ms
Risk FOUT — text flashes from fallback to web font
woff2;base64,d09GMgABAA... woff2 swap
Size 63 KB
Load time 24 ms
Start 753 ms
Risk FOUT — text flashes from fallback to web font
Manrope-VariableFont_wg... woff2 swap
Size 0 KB
Load time -2826 ms
Start 2.8 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/8780de57-19d4-44df-9d71-c1148a49d76e-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
21 resources · 431 KB · 0 KB savings available
PASS
21 resources · 431 KB · 0 KB savings available
Info::
Within 1MB page-weight target
Got: 431 KB
Info::
10 third-party resources (38% of weight)
21 resources · 430.5 KiB · 10 third-party Within 1MB page-weight target
CSS 45% · 193.3 KiB
Font 28% · 121.8 KiB
Image 14% · 61.8 KiB
JavaScript 6% · 27.8 KiB
Document 5% · 20.2 KiB
Other 1% · 5.7 KiB
Network Waterfall
21 requests over 3157ms
INFO
0 ms 1.0 s 2.0 s 3.0 s FCP 772 ms LCP 813 mshttps://ibiblio.org// https://ibiblio.org/ — 200 — 2.7 KiB — 321 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 — 416 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 — 218 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 — 414 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 — 308 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 — 104 ms — http/1.1data:font/woff2;base64,d09GMgABAAAAAOykABQAAAACdZgAAOwyAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGoUNG4LYfByR…data:font/woff2;base64,d09GMgABAAAA... data:font/woff2;base64,d09GMgABAAAAAOykABQAAAACdZgAAOwyAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGoUNG4LYfByR… — 200 — 59.2 KiB — 20 ms — datadata:font/woff2;base64,d09GMgABAAAAAPq4ABUAAAACTIQAAPo7AAFmqAAAAAAAAAAAAAAAAAAAAAAAAAAAGokqG4Hrchya…data:font/woff2;base64,d09GMgABAAAA... data:font/woff2;base64,d09GMgABAAAAAPq4ABUAAAACTIQAAPo7AAFmqAAAAAAAAAAAAAAAAAAAAAAAAAAAGokqG4Hrchya… — 200 — 62.7 KiB — 24 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 — 118 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 — 119 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=019db1ea-3a83-7cea-b309-fbdb494a2686&response=000042fdada826557c0a85bea4e84ea23d8af95e99d3854d455a50a5d696ccd5&nonce=144381&redir=https%3A%2F%2Fibiblio.org%2F&elapsedTime=1263/.within.website/x/cmd/anubis/api/p... https://ibiblio.org/.within.website/x/cmd/anubis/api/pass-challenge?id=019db1ea-3a83-7cea-b309-fbdb494a2686&response=000042fdada826557c0a85bea4e84ea23d8af95e99d3854d455a50a5d696ccd5&nonce=144381&redir=https%3A%2F%2Fibiblio.org%2F&elapsedTime=1263 — 302 — 739 B — 106 ms — http/1.1https://ibiblio.org// https://ibiblio.org/ — 301 — 208 B — 125 ms — http/1.1https://www.ibiblio.org/www.ibiblio.org/ https://www.ibiblio.org/ — 200 — 16.5 KiB — 422 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 — 130 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 — 238 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 — 318 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 — 298 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 — -1 — 0 B — 0 ms — blob:https://www.ibiblio.org/8780de57-19d4-44df-9d71-c1148a49d76ewww.ibiblio.org/8780de57-19d4-44df-... blob:https://www.ibiblio.org/8780de57-19d4-44df-9d71-c1148a49d76e — 200 — -1 B — 30 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 — 106 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 253ms · 17KB · $3/mo
www.ibiblio.org
Other
Optional
Execution 177ms
Transfer 17 KB
Monthly Cost $2/mo
Unattributable
Other
Optional
Execution 77ms
Transfer 0 KB
Monthly Cost $1/mo

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

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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