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Performance

· 17 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
95
GRADE
A
FIX
1
REVIEW
3
PASS
11
INFO
2

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

Mobile Desktop
90
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
57
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
88
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
75
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.

1.08 s

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

3.26 s

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

92 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.

3.92 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.

3.26 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 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::
ETag present — enables conditional (304) responses
Info::
Last-Modified header present

No Cache-Control header

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

C
Image Optimization
Action
9 images, 0 KB saveable
REVIEW
9 images, 0 KB saveable
Warning::
https://openjdk.org/images/duke-plug.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://openjdk.org/images/duke-chalkboard.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://openjdk.org/images/duke-pipes.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://openjdk.org/images/duke-thinking.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
9 images 53 KB
0 oversized -0 KB
7 legacy format
4 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

B
JS Execution Cost
986ms total JS execution
REVIEW
986ms total JS execution
Warning::
https://openjdk.org/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fi...: 709ms CPU time
Info::
Unattributable: 174ms CPU time
Info::
https://openjdk.org/akam/13/3ce02fab: 103ms CPU time
Info::
Third-party scripts: 174ms (18% of total)

Main Thread Breakdown

Script Evaluation 69% Other 17% Style & Layout 7% Script Parsing & Compilation 4%
ScriptTotalScriptingParse/CompileParty
https://openjdk.org/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbzJb3i0N8h7Dip/SF4jOnQD/bgpa/ViQeFBEB709ms592ms40ms1st
Unattributable174ms32ms0ms3rd
https://openjdk.org/akam/13/3ce02fab103ms92ms5ms1st
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
295 KB transferred, 26 requests
PASS
295 KB transferred, 26 requests
Info::
Page weighs 694 KB (295 KB transferred)
Info::
26 HTTP requests
Info::
Estimated 0.06 g CO2 per page load
295 KB / 2.4 MB budget
295 KB transferred
26 requests
0.06 g CO2 per page load
JavaScript 186.9 KiB 63%
Images 52.9 KiB 18%
Fonts 42.8 KiB 15%
HTML 6.0 KiB 2%
CSS 2.8 KiB 1%
Other 2.4 KiB 1%
Other 1.3 KiB 0%
0 2.4 MB 4.9 MB
Under budget
A+
Third-Party Impact
1% third-party, 0 ms blocking
PASS
1% third-party, 0 ms blocking
Info::
Third-party code accounts for 1% of page weight (3.1 KiB of 295.1 KiB)
Info::
Third-party blocking time is low (0 ms)
99%
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 (43 KB)
PASS
2 fonts (43 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

43 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 1.0 s 2.0 s 3.0 s FCP 1.1 s LCP 3.3 shttps://openjdk.org/.fonts/DejaVuSans-webfont.woffDejaVuSans-webfont.woff https://openjdk.org/.fonts/DejaVuSans-webfont.woff — 21.4 KiB — 14 ms — font-display: swaphttps://openjdk.org/.fonts/DejaVuSans-Bold-webfont.woffDejaVuSans-Bold-webfont... https://openjdk.org/.fonts/DejaVuSans-Bold-webfont.woff — 21.4 KiB — 15 ms — font-display: swap
DejaVuSans-webfont.woff woff swap
Size 21 KB
Load time 14 ms
Start 1.9 s
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
DejaVuSans-Bold-webfont... woff swap
Size 21 KB
Load time 15 ms
Start 1.9 s
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
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 ~13 KB and ~26 ms

A+
JS Bundles
5 scripts, 37 KB unused
PASS
5 scripts, 37 KB unused
Warning::
https://openjdk.org/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fi...: 37 KB unused (21%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 37 KB
37 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://openjdk.org/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbzJb3i0N8h7Dip/SF4jOnQD/bgpa/ViQeFBEB174 KB37 KB (21%)✓1st
https://openjdk.org/page.js1 KB—✓1st
https://cdn.usefathom.com/script.js3 KB—✓3rd
https://openjdk.org/akam/13/3ce02fab9 KB—✓1st
blob:https://openjdk.org/e28114ab-4818-443a-9fa2-55048b3ef78a0 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

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
26 resources · 295 KB · 37 KB savings available
PASS
26 resources · 295 KB · 37 KB savings available
Info::
Within 1MB page-weight target
Got: 295 KB
Info::
8 third-party resources (1% of weight)
26 resources · 295.1 KiB · 8 third-party Within 1MB page-weight target
JavaScript 63% · 186.9 KiB
Image 18% · 54.2 KiB
Font 15% · 42.8 KiB
Document 2% · 6.6 KiB
CSS 1% · 2.8 KiB
Other 1% · 1.9 KiB

~37.0 KiB of savings available

Remove unused JavaScript: 37.0 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
26 requests over 3209ms
INFO
0 ms 1.0 s 2.0 s 3.0 s FCP 1.1 s LCP 3.3 shttps://openjdk.org// https://openjdk.org/ — 200 — 6.0 KiB — 380 ms — h2https://openjdk.org/page.css/page.css https://openjdk.org/page.css — 200 — 1.6 KiB — 733 ms — h2https://openjdk.org/page.js/page.js https://openjdk.org/page.js — 200 — 1.1 KiB — 15 ms — h2https://openjdk.org/images/openjdk2.svg/images/openjdk2.svg https://openjdk.org/images/openjdk2.svg — 200 — 2.3 KiB — 16 ms — h2https://openjdk.org/images/duke-thinking.png/images/duke-thinking.png https://openjdk.org/images/duke-thinking.png — 200 — 14.8 KiB — 58 ms — h2https://openjdk.org/images/duke-plug.png/images/duke-plug.png https://openjdk.org/images/duke-plug.png — 200 — 11.7 KiB — 42 ms — h2https://openjdk.org/images/duke-chalkboard.png/images/duke-chalkboard.png https://openjdk.org/images/duke-chalkboard.png — 200 — 8.8 KiB — 21 ms — h2https://openjdk.org/images/duke-pipes.png/images/duke-pipes.png https://openjdk.org/images/duke-pipes.png — 200 — 12.6 KiB — 18 ms — h2https://openjdk.org/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbzJb3i0N8h7Dip/SF4jOnQD/bgpa/ViQeFBEB/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbz... https://openjdk.org/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbzJb3i0N8h7Dip/SF4jOnQD/bgpa/ViQeFBEB — 200 — 173.8 KiB — 745 ms — h2https://cdn.usefathom.com/script.jscdn.usefathom.com/script.js https://cdn.usefathom.com/script.js — 200 — 2.7 KiB — 35 ms — h2https://openjdk.org/.fonts/dejavu.css/.fonts/dejavu.css https://openjdk.org/.fonts/dejavu.css — 200 — 1.2 KiB — 704 ms — h2https://openjdk.org/akam/13/3ce02fab/akam/13/3ce02fab https://openjdk.org/akam/13/3ce02fab — 200 — 9.3 KiB — 465 ms — h2https://openjdk.org/images/oracle.svg/images/oracle.svg https://openjdk.org/images/oracle.svg — 200 — 2.3 KiB — 17 ms — h2https://openjdk.report-uri.io/r/default/csp/reportOnlyopenjdk.report-uri.io/r/default/csp... https://openjdk.report-uri.io/r/default/csp/reportOnly — -1 — 0 B — 110 ms — https://openjdk.org/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbzJb3i0N8h7Dip/SF4jOnQD/bgpa/ViQeFBEB/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbz... https://openjdk.org/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbzJb3i0N8h7Dip/SF4jOnQD/bgpa/ViQeFBEB — 201 — 930 B — 254 ms — h2https://openjdk.org/.fonts/DejaVuSans-webfont.woff/.fonts/DejaVuSans-webfont.woff https://openjdk.org/.fonts/DejaVuSans-webfont.woff — 200 — 21.4 KiB — 14 ms — h2https://openjdk.org/.fonts/DejaVuSans-Bold-webfont.woff/.fonts/DejaVuSans-Bold-webfont.wof... https://openjdk.org/.fonts/DejaVuSans-Bold-webfont.woff — 200 — 21.4 KiB — 15 ms — h2data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAASwAAACWCAYAAABkW7XSAAAQAElEQVR4AeycCXzVNbbHk3tbyl5AN…data:image/png;base64,iVBORw0KGgoAA... data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAASwAAACWCAYAAABkW7XSAAAQAElEQVR4AeycCXzVNbbHk3tbyl5AN… — 200 — 0 B — 0 ms — datadata:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAACGFjVEwAAAABAAAAAcMq2TYAAAANS…data:image/png;base64,iVBORw0KGgoAA... data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAACGFjVEwAAAABAAAAAcMq2TYAAAANS… — 200 — 0 B — 0 ms — datahttps://openjdk.report-uri.io/r/default/csp/reportOnlyopenjdk.report-uri.io/r/default/csp... https://openjdk.report-uri.io/r/default/csp/reportOnly — -1 — 0 B — 21 ms — https://cdn.usefathom.com/?h=https%3A%2F%2Fopenjdk.org&p=%2F&r=&sid=KCYJJPZX&qs=%7B%7D&cid=18935488cdn.usefathom.com/?h=https%3A%2F%2F... https://cdn.usefathom.com/?h=https%3A%2F%2Fopenjdk.org&p=%2F&r=&sid=KCYJJPZX&qs=%7B%7D&cid=18935488 — 200 — 433 B — 162 ms — h2https://openjdk.org/images/nanoduke.ico/images/nanoduke.ico https://openjdk.org/images/nanoduke.ico — 200 — 1.3 KiB — 15 ms — h2https://openjdk.org/akam/13/pixel_3ce02fab/akam/13/pixel_3ce02fab https://openjdk.org/akam/13/pixel_3ce02fab — 200 — 579 B — 10 ms — h2https://openjdk.report-uri.io/r/default/csp/reportOnlyopenjdk.report-uri.io/r/default/csp... https://openjdk.report-uri.io/r/default/csp/reportOnly — -1 — 0 B — 22 ms — blob:https://openjdk.org/e28114ab-4818-443a-9fa2-55048b3ef78aopenjdk.org/e28114ab-4818-443a-9fa2... blob:https://openjdk.org/e28114ab-4818-443a-9fa2-55048b3ef78a — -1 — 0 B — 0 ms — https://openjdk.org/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbzJb3i0N8h7Dip/SF4jOnQD/bgpa/ViQeFBEB/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbz... https://openjdk.org/3AaSu3zE/qBvsWf4/ZlJ9obh/Hu/fiapbzJb3i0N8h7Dip/SF4jOnQD/bgpa/ViQeFBEB — 201 — 978 B — 217 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
18% of JavaScript execution is third-party
First-party Third-party 174ms · 0KB · $2/mo
Unattributable
Other
Optional
Execution 174ms
Transfer 0 KB
Monthly Cost $2/mo

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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