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Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
88
GRADE
B
FIX
1
REVIEW
3
PASS
10
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.
73
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.

4.30 s

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

7.66 s

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

285 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.

6.05 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.

7.68 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
10 PASS 3 REVIEW 1 FIX
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
21 images, 0 KB saveable
REVIEW
21 images, 0 KB saveable
Warning::
https://www.scala-lang.org/resources/img/frontpage... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.scala-lang.org/resources/img/frontpage... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.scala-lang.org/resources/img/frontpage... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.scala-lang.org/resources/img/frontpage... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.scala-lang.org/resources/img/frontpage... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.scala-lang.org/resources/img/frontpage... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.scala-lang.org/resources/img/frontpage... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.scala-lang.org/resources/img/frontpage... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.scala-lang.org/resources/img/frontpage... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.scala-lang.org/resources/img/frontpage... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
21 images 374 KB
0 oversized -0 KB
21 legacy format
10 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

C
JS Execution Cost
Action
1337ms total JS execution
REVIEW
1337ms total JS execution
Warning::
https://ajax.googleapis.com/ajax/libs/jquery/3.1.1...: 357ms CPU time
Warning::
Unattributable: 321ms CPU time
Warning::
https://www.scala-lang.org/: 266ms CPU time
Warning::
https://plausible.scala-lang.org/js/script.js: 265ms CPU time
Info::
https://cdnjs.cloudflare.com/ajax/libs/highlight.j...: 76ms CPU time
Warning::
Third-party scripts: 1019ms (76% of total)

Main Thread Breakdown

Script Evaluation 29% Other 28% Style & Layout 28% Script Parsing & Compilation 7% Parse HTML & CSS 6%
ScriptTotalScriptingParse/CompileParty
https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js357ms261ms15ms3rd
Unattributable321ms6ms0ms3rd
https://www.scala-lang.org/266ms14ms1ms1st
https://plausible.scala-lang.org/js/script.js265ms17ms1ms3rd
https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.5.1/highlight.min.js76ms61ms14ms3rd
https://www.scala-lang.org/resources/js/vendor/codemirror/codemirror.js52ms8ms44ms1st
B
JS Bundles
15 scripts, 78 KB unused
REVIEW
15 scripts, 78 KB unused
Warning::
https://www.scala-lang.org/resources/js/vendor/cod...: 78 KB unused (83%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.scala-lang.org/resources/js/vendor/cod...: unminified — 31 KB could be saved
Info::
Total unused JavaScript: 78 KB
78 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.scala-lang.org/resources/js/vendor/codemirror/codemirror.js94 KB78 KB (83%)✗1st
https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.5.1/highlight.min.js35 KB—✓3rd
https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.5.1/languages/java.min.js2 KB—✓3rd
https://www.scala-lang.org/resources/js/vendor/prettify/prettify.js6 KB—✓1st
https://www.scala-lang.org/resources/js/vendor/prettify/lang-scala.js1 KB—✓1st
https://www.scala-lang.org/resources/js/vendor/unslider.js7 KB—✗1st
https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js30 KB—✓3rd
https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.5.1/languages/scala.min.js1 KB—✓3rd
https://www.scala-lang.org/resources/js/tweetMachine-update.js5 KB—✗1st
https://www.scala-lang.org/resources/js/hljs-scala3.js4 KB—✓1st

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
Page Weight Budget
959 KB transferred, 58 requests
PASS
959 KB transferred, 58 requests
Info::
Page weighs 1.7 MB (959 KB transferred)
Info::
Fonts are 312 KB — consider subsetting or using system fonts
Subset fonts to include only used characters, or switch to system font stacks.
Got: 312 KB
Info::
58 HTTP requests
Info::
Estimated 0.20 g CO2 per page load
959 KB / 2.4 MB budget
959 KB transferred
58 requests
0.20 g CO2 per page load
Images 373.9 KiB 39%
Fonts 312.4 KiB 33%
JavaScript 210.0 KiB 22%
CSS 44.5 KiB 5%
HTML 13.6 KiB 1%
Other 3.1 KiB 0%
Other 651 B 0%
Other 437 B 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
37% third-party, 0 ms blocking
PASS
37% third-party, 0 ms blocking
Info::
Third-party code accounts for 37% of page weight (353.1 KiB of 958.5 KiB)
Info::
Third-party blocking time is low (0 ms)
63%
37%
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
6 fonts (312 KB)
PASS
6 fonts (312 KB)
Info::
6 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

6

312 KB total

Render-blocking

0

of 6

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 7.0 s 8.0 s FCP 4.3 s LCP 7.7 shttps://fonts.gstatic.com/s/lato/v25/S6u9w4BMUTPHh50XSwiPGQ3q5d0.woff2S6u9w4BMUTPHh50XSwiPGQ3... https://fonts.gstatic.com/s/lato/v25/S6u9w4BMUTPHh50XSwiPGQ3q5d0.woff2 — 13.4 KiB — 0 ms — font-display: swaphttps://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://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.2/webfonts/fa-solid-900.woff2fa-solid-900.woff2 https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.2/webfonts/fa-solid-900.woff2 — 153.4 KiB — 0 ms — font-display: swaphttps://www.scala-lang.org/resources/glyphs/Inconsolata_SemiExpanded-SemiBold.ttfInconsolata_SemiExpande... https://www.scala-lang.org/resources/glyphs/Inconsolata_SemiExpanded-SemiBold.ttf — 50.7 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/robotoslab/v36/BngMUXZYTXPIvIBgJJSb6ufN5qWr4xCC.woff2BngMUXZYTXPIvIBgJJSb6uf... https://fonts.gstatic.com/s/robotoslab/v36/BngMUXZYTXPIvIBgJJSb6ufN5qWr4xCC.woff2 — 33.4 KiB — 0 ms — font-display: swaphttps://fonts.gstatic.com/s/caveat/v23/WnznHAc5bAfYB2QRah7pcpNvOx-pjfJ9eIWpYT5Mmgo.woff2WnznHAc5bAfYB2QRah7pcpN... https://fonts.gstatic.com/s/caveat/v23/WnznHAc5bAfYB2QRah7pcpNvOx-pjfJ9eIWpYT5Mmgo.woff2 — 47.7 KiB — 0 ms — font-display: swap
S6u9w4BMUTPHh50XSwiPGQ3... woff2 swap
Size 13 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
S6uyw4BMUTPHjx4wXiWtFCc... woff2 swap
Size 14 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
fa-solid-900.woff2 woff2 swap
Size 153 KB
Load time 0 ms
Start 0 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
Inconsolata_SemiExpande... ttf swap
Size 51 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
  • Convert to woff2 for ~30% smaller file size
BngMUXZYTXPIvIBgJJSb6uf... woff2 swap
Size 33 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
WnznHAc5bAfYB2QRah7pcpN... woff2 swap
Size 48 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)

Fixing the unchecked items could save ~92 KB and ~184 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+
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
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Cloudflare

Network Waterfall
58 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
76% of JavaScript execution is third-party
First-party Third-party 1019ms · 66KB · $3/mo
ajax.googleapis.com
Other
Costly
Execution 357ms
Transfer 30 KB
Monthly Cost $1/mo
Unattributable
Other
Costly
Execution 321ms
Transfer 0 KB
Monthly Cost $1/mo
plausible.scala-lang.org
Other
Costly
Execution 265ms
Transfer 1 KB
Monthly Cost $1/mo
cdnjs
CDN
Optional
Execution 76ms
Transfer 35 KB
Monthly Cost $0/mo

These scripts may cost more than they're worth

  • ajax.googleapis.com adds 357ms and costs ~$1/month
  • Unattributable adds 321ms and costs ~$1/month
  • plausible.scala-lang.org adds 265ms and costs ~$1/month

76% 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

ajax.googleapis.com takes 357ms 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

Unattributable takes 321ms 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

plausible.scala-lang.org takes 265ms 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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