Skip to content
https://www.scala-lang.org

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
88
GRADE
B
FIX
1
REVIEW
2
PASS
9
INFO
2

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

Mobile Desktop
94
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.

944 ms

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

1.40 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.

0.002

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

944 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.

1.40 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
14
9 PASS 2 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
22 images, 0 KB saveable
REVIEW
22 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.
22 images 386 KB
0 oversized -0 KB
22 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

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
970 KB transferred, 59 requests
PASS
970 KB transferred, 59 requests
Info::
Page weighs 1.7 MB (970 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::
59 HTTP requests
Info::
Estimated 0.20 g CO2 per page load
970 KB / 2.4 MB budget
970 KB transferred
59 requests
0.20 g CO2 per page load
Images 385.7 KiB 40%
Fonts 312.2 KiB 32%
JavaScript 210.0 KiB 22%
CSS 44.6 KiB 5%
HTML 13.6 KiB 1%
Other 3.1 KiB 0%
Other 643 B 0%
Other 439 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
36% third-party, 0 ms blocking
PASS
36% third-party, 0 ms blocking
Info::
Third-party code accounts for 36% of page weight (353.1 KiB of 970.4 KiB)
Info::
Third-party blocking time is low (0 ms)
64%
36%
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+
JS Execution Cost
320ms total JS execution
PASS
320ms total JS execution
Info::
https://www.scala-lang.org/: 175ms CPU time
Info::
Unattributable: 80ms CPU time
Info::
https://ajax.googleapis.com/ajax/libs/jquery/3.1.1...: 65ms CPU time
Info::
Third-party scripts: 145ms (45% of total)

Main Thread Breakdown

Style & Layout 36% Other 26% Script Evaluation 23% Script Parsing & Compilation 7% Parse HTML & CSS 5% Rendering 3%
ScriptTotalScriptingParse/CompileParty
https://www.scala-lang.org/175ms3ms0ms1st
Unattributable80ms2ms0ms3rd
https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js65ms50ms8ms3rd
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 500 ms 1.0 s FCP 944 ms LCP 1.4 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 — 50.6 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-pjfJ9eIWpYT5Kmgq3sw.woff2WnznHAc5bAfYB2QRah7pcpN... https://fonts.gstatic.com/s/caveat/v23/WnznHAc5bAfYB2QRah7pcpNvOx-pjfJ9eIWpYT5Kmgq3sw.woff2 — 47.8 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+
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
59 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
45% of JavaScript execution is third-party
First-party Third-party 145ms · 30KB · $0/mo
Unattributable
Other
Optional
Execution 80ms
Transfer 0 KB
Monthly Cost $0/mo
ajax.googleapis.com
Other
Optional
Execution 65ms
Transfer 30 KB
Monthly Cost $0/mo

45% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

Learn more ▾

Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

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.

Send Feedback