Skip to content
https://typescriptlang.org

Performance

· 22 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
89
GRADE
B
FIX
2
REVIEW
7
PASS
10
INFO
3

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

Mobile Desktop
96
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.
100
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.

1.06 s

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

1.06 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.

0.059

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

1.06 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.

1.06 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
22
10 PASS 7 REVIEW 2 FIX
D
Third-Party Impact
Action
100% third-party, 0 ms blocking
FIX
100% third-party, 0 ms blocking
Warning::
Third-party code accounts for 100% of page weight (835.0 KiB of 835.1 KiB)
Info::
Third-party blocking time is low (0 ms)
100%
First-party Third-party
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.

No Cache-Control header

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

C
Image Optimization
Action
10 images, 0 KB saveable
REVIEW
10 images, 0 KB saveable
Warning::
https://www.typescriptlang.org/images/index/stack-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.typescriptlang.org/images/index/state-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
10 images 51 KB
0 oversized -0 KB
8 legacy format
2 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

B
JS Bundles
7 scripts, 95 KB unused
REVIEW
7 scripts, 95 KB unused
Warning::
https://www.typescriptlang.org/commons-a43cb90ce2f...: 42 KB unused (71%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.typescriptlang.org/app-9b3a6007d51cd72...: 28 KB unused (38%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.typescriptlang.org/js/docsearch.js: 26 KB unused (56%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 95 KB
95 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.typescriptlang.org/commons-a43cb90ce2f9a5d36341.js63 KB42 KB (71%)✓3rd
https://www.typescriptlang.org/app-9b3a6007d51cd726e84d.js73 KB28 KB (38%)✓3rd
https://www.typescriptlang.org/js/docsearch.js46 KB26 KB (56%)✓3rd
https://www.typescriptlang.org/webpack-runtime-fdfe43fe0945c45d4db4.js3 KB—✓3rd
https://www.typescriptlang.org/07c2af5afdf750a1639f84255225a64498e50277-0400cf63dd5d2e08696b.js23 KB—✓3rd
https://www.typescriptlang.org/component---src-templates-pages-index-tsx-a723abe51a93c1625181.js40 KB—✓3rd
https://consentdeliveryfd.azurefd.net/mscc/lib/v2/wcp-consent.js277 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

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

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

B
HTTP/3 (QUIC)
HTTP/3 not advertised
REVIEW
HTTP/3 not advertised
Info::
HTTP/3 (QUIC) is not advertised
HTTP/3 isn't advertised via Alt-Svc and the worker didn't negotiate h3. HTTP/3 reduces handshake latency (1-RTT instead of 2-3 RTTs) and is more resilient on lossy connections. Most modern CDNs (Cloudflare, Fastly, AWS CloudFront, Google Cloud CDN) support HTTP/3 with a single config switch -- consider enabling for mobile-heavy workloads.
C
Compression Algorithm
Action
Main response served uncompressed
REVIEW
Main response served uncompressed
Info::
Main HTML response has no Content-Encoding (uncompressed)
The main HTML document is served without compression. The Text Compression section above lists the broader picture; for the main response specifically, even gzip would shave ~70-80% off most text payloads.
B
Main HTML Cache-Control
No Cache-Control header on main HTML response
REVIEW
No Cache-Control header on main HTML response
Info::
Main HTML response has no Cache-Control header
Without an explicit Cache-Control, browsers fall back to heuristic caching (~10% of Last-Modified age). Set `Cache-Control: no-cache` or `max-age=300` for HTML to control freshness explicitly -- prevents stale auth state and SPA shell drift.
B
Server-Timing Observability
No Server-Timing header found
REVIEW
No Server-Timing header found
Info::
No Server-Timing header found
Server-Timing exposes backend timing breakdowns to browser DevTools (e.g., `db: 45ms; render: 120ms; cache: 2ms`). Useful for diagnosing slow pages without backend log access. Most modern frameworks (Next.js, Cloudflare Workers, Fastly) emit it automatically; absence on a managed platform usually means telemetry headers are stripped at the edge.
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A
Page Weight Budget
835 KB transferred, 30 requests
PASS
835 KB transferred, 30 requests
Info::
Page weighs 1.6 MB (835 KB transferred)
Warning::
JavaScript is 525 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 525 KB
Info::
30 HTTP requests
Info::
Estimated 0.17 g CO2 per page load
835 KB / 2.4 MB budget
835 KB transferred
30 requests
0.17 g CO2 per page load
JavaScript 525.4 KiB 63%
Fonts 175.9 KiB 21%
HTML 69.2 KiB 8%
Images 51.4 KiB 6%
Other 6.0 KiB 1%
CSS 5.9 KiB 1%
Other 736 B 0%
Other 569 B 0%
0 2.4 MB 4.9 MB
Under budget

Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.

Why this matters

JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.

Source: web.dev

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
257ms total JS execution
PASS
257ms total JS execution
Info::
https://www.typescriptlang.org/: 127ms CPU time
Info::
https://www.typescriptlang.org/app-9b3a6007d51cd72...: 70ms CPU time
Info::
Unattributable: 59ms CPU time
Warning::
Third-party scripts: 197ms (77% of total)

Main Thread Breakdown

Other 28% Script Evaluation 28% Style & Layout 25% Script Parsing & Compilation 8% Rendering 7% Parse HTML & CSS 4%
ScriptTotalScriptingParse/CompileParty
https://www.typescriptlang.org/127ms3ms1ms3rd
https://www.typescriptlang.org/app-9b3a6007d51cd726e84d.js70ms53ms5ms3rd
Unattributable59ms1ms0ms1st
A+
Font Loading
5 fonts (176 KB)
PASS
5 fonts (176 KB)
Info::
5 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

5

176 KB total

Render-blocking

0

of 5

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s FCP 1.1 s LCP 1.1 shttps://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-semibold.woff2segoeui-semibold.woff2 https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-semibold.woff2 — 31.1 KiB — 21 ms — font-display: swaphttps://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-regular.woff2segoeui-regular.woff2 https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-regular.woff2 — 35.5 KiB — 39 ms — font-display: swaphttps://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-light.woff2segoeui-light.woff2 https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-light.woff2 — 28.1 KiB — 41 ms — font-display: swaphttps://www.typescriptlang.org/fonts/CascadiaMono-SemiLight.woff2CascadiaMono-SemiLight.... https://www.typescriptlang.org/fonts/CascadiaMono-SemiLight.woff2 — 49.0 KiB — 4 ms — font-display: swaphttps://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-bold.woff2segoeui-bold.woff2 https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-bold.woff2 — 32.2 KiB — 39 ms — font-display: swap
segoeui-semibold.woff2 woff2 swap
Size 31 KB
Load time 21 ms
Start 387 ms
Risk FOUT — text flashes from fallback to web font
segoeui-regular.woff2 woff2 swap
Size 36 KB
Load time 39 ms
Start 388 ms
Risk FOUT — text flashes from fallback to web font
segoeui-light.woff2 woff2 swap
Size 28 KB
Load time 41 ms
Start 388 ms
Risk FOUT — text flashes from fallback to web font
CascadiaMono-SemiLight.... woff2 swap
Size 49 KB
Load time 4 ms
Start 389 ms
Risk FOUT — text flashes from fallback to web font
segoeui-bold.woff2 woff2 swap
Size 32 KB
Load time 39 ms
Start 389 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)
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+
LCP Image Preload
LCP preload audit not available
PASS
LCP preload audit not available
Info::
LCP image preload audit not available for this scan
A+
Server Response Intelligence
1 server-response signal(s) detected
PASS
1 server-response signal(s) detected
Info::
No `ETag` or `Last-Modified` -- conditional GET not supported
Without either header, browsers can't issue conditional GETs and refresh always re-downloads the full response body even when nothing changed. Add `ETag: "<hash>"` (or `Last-Modified: <date>`) on cacheable responses; the server returns 304 Not Modified when the client's cached copy is still valid, saving bandwidth.
A
Page Weight Inventory
30 resources · 835 KB · 95 KB savings available
PASS
30 resources · 835 KB · 95 KB savings available
Info::
Within 1MB page-weight target
Got: 835 KB
Info::
~95 KB of savings available
Warning::
29 third-party resources (100% of weight)
Info::
1 resources over 200KB
30 resources · 835.1 KiB · 29 third-party Within 1MB page-weight target
JavaScript 63% · 525.4 KiB
Font 21% · 175.9 KiB
Document 8% · 69.2 KiB
Image 7% · 57.2 KiB
CSS 1% · 5.9 KiB
Other 0% · 1.4 KiB

~95.4 KiB of savings available

Remove unused JavaScript: 95.4 KiB
Network Waterfall
30 requests over 1766ms
INFO
0 ms 500 ms 1.0 s 1.5 s FCP 1.1 s LCP 1.1 shttps://typescriptlang.org// https://typescriptlang.org/ — 301 — 135 B — 293 ms — h2https://www.typescriptlang.org/www.typescriptlang.org/ https://www.typescriptlang.org/ — 200 — 69.2 KiB — 16 ms — h2https://www.typescriptlang.org/css/docsearch.csswww.typescriptlang.org/css/docsearc... https://www.typescriptlang.org/css/docsearch.css — 200 — 5.9 KiB — 6 ms — h2https://www.typescriptlang.org/images/index/stack-overflow.svgwww.typescriptlang.org/images/index... https://www.typescriptlang.org/images/index/stack-overflow.svg — 200 — 13.2 KiB — 10 ms — h2https://www.typescriptlang.org/images/index/state-of-js.svgwww.typescriptlang.org/images/index... https://www.typescriptlang.org/images/index/state-of-js.svg — 200 — 3.4 KiB — 3 ms — h2https://www.typescriptlang.org/webpack-runtime-fdfe43fe0945c45d4db4.jswww.typescriptlang.org/webpack-runt... https://www.typescriptlang.org/webpack-runtime-fdfe43fe0945c45d4db4.js — 200 — 3.1 KiB — 3 ms — h2https://www.typescriptlang.org/app-9b3a6007d51cd726e84d.jswww.typescriptlang.org/app-9b3a6007... https://www.typescriptlang.org/app-9b3a6007d51cd726e84d.js — 200 — 72.9 KiB — 5 ms — h2data:image/svg+xml,%3Csvg%20xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg'%20viewBox%3D'0%200%206%2…data:image/svg+xml,%3Csvg%20xmlns%3... data:image/svg+xml,%3Csvg%20xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg'%20viewBox%3D'0%200%206%2… — 200 — 0 B — 0 ms — datahttps://www.typescriptlang.org/images/index/get-started-handbook.svgwww.typescriptlang.org/images/index... https://www.typescriptlang.org/images/index/get-started-handbook.svg — 200 — 4.8 KiB — 132 ms — h2https://www.typescriptlang.org/images/index/get-started-playground.svgwww.typescriptlang.org/images/index... https://www.typescriptlang.org/images/index/get-started-playground.svg — 200 — 7.2 KiB — 119 ms — h2https://www.typescriptlang.org/images/index/get-started-download.svgwww.typescriptlang.org/images/index... https://www.typescriptlang.org/images/index/get-started-download.svg — 200 — 6.2 KiB — 118 ms — h2https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-semibold.woff2res-1.cdn.office.net/files/fabric-c... https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-semibold.woff2 — 200 — 31.1 KiB — 21 ms — h3https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-regular.woff2res-1.cdn.office.net/files/fabric-c... https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-regular.woff2 — 200 — 35.5 KiB — 39 ms — h3https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-light.woff2res-1.cdn.office.net/files/fabric-c... https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-light.woff2 — 200 — 28.1 KiB — 41 ms — h3https://www.typescriptlang.org/fonts/CascadiaMono-SemiLight.woff2www.typescriptlang.org/fonts/Cascad... https://www.typescriptlang.org/fonts/CascadiaMono-SemiLight.woff2 — 200 — 49.0 KiB — 4 ms — h2https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-bold.woff2res-1.cdn.office.net/files/fabric-c... https://res-1.cdn.office.net/files/fabric-cdn-prod_20230815.002/assets/fonts/segoeui-westeuropean/segoeui-bold.woff2 — 200 — 32.2 KiB — 39 ms — h3data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAALgAAAAmCAYAAAB3X1H0AAAACXBIWXMAABYlAAAWJQFJUiTwAAAAA…data:image/png;base64,iVBORw0KGgoAA... data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAALgAAAAmCAYAAAB3X1H0AAAACXBIWXMAABYlAAAWJQFJUiTwAAAAA… — 200 — 0 B — 0 ms — datahttps://www.typescriptlang.org/images/index/get-started-handbook-blue.svgwww.typescriptlang.org/images/index... https://www.typescriptlang.org/images/index/get-started-handbook-blue.svg — 200 — 5.0 KiB — 119 ms — h2https://www.typescriptlang.org/images/index/get-started-playground-blue.svgwww.typescriptlang.org/images/index... https://www.typescriptlang.org/images/index/get-started-playground-blue.svg — 200 — 5.7 KiB — 128 ms — h2https://www.typescriptlang.org/images/index/get-started-download-blue.svgwww.typescriptlang.org/images/index... https://www.typescriptlang.org/images/index/get-started-download-blue.svg — 200 — 5.9 KiB — 130 ms — h2https://www.typescriptlang.org/manifest.webmanifestwww.typescriptlang.org/manifest.web... https://www.typescriptlang.org/manifest.webmanifest — 200 — 736 B — 13 ms — h2https://www.typescriptlang.org/page-data/app-data.jsonwww.typescriptlang.org/page-data/ap... https://www.typescriptlang.org/page-data/app-data.json — 200 — 211 B — 7 ms — h2https://www.typescriptlang.org/page-data/index/page-data.jsonwww.typescriptlang.org/page-data/in... https://www.typescriptlang.org/page-data/index/page-data.json — 200 — 358 B — 6 ms — h2https://www.typescriptlang.org/commons-a43cb90ce2f9a5d36341.jswww.typescriptlang.org/commons-a43c... https://www.typescriptlang.org/commons-a43cb90ce2f9a5d36341.js — 200 — 62.5 KiB — 9 ms — h2https://www.typescriptlang.org/07c2af5afdf750a1639f84255225a64498e50277-0400cf63dd5d2e08696b.jswww.typescriptlang.org/07c2af5afdf7... https://www.typescriptlang.org/07c2af5afdf750a1639f84255225a64498e50277-0400cf63dd5d2e08696b.js — 200 — 23.2 KiB — 8 ms — h2https://www.typescriptlang.org/component---src-templates-pages-index-tsx-a723abe51a93c1625181.jswww.typescriptlang.org/component---... https://www.typescriptlang.org/component---src-templates-pages-index-tsx-a723abe51a93c1625181.js — 200 — 39.9 KiB — 8 ms — h2https://consentdeliveryfd.azurefd.net/mscc/lib/v2/wcp-consent.jsconsentdeliveryfd.azurefd.net/mscc/... https://consentdeliveryfd.azurefd.net/mscc/lib/v2/wcp-consent.js — 200 — 277.4 KiB — 1.2 s — h2https://www.typescriptlang.org/js/docsearch.jswww.typescriptlang.org/js/docsearch... https://www.typescriptlang.org/js/docsearch.js — 200 — 46.4 KiB — 5 ms — h2https://www.typescriptlang.org/favicon-32x32.png?v=8944a05a8b601855de116c8a56d3b3aewww.typescriptlang.org/favicon-32x3... https://www.typescriptlang.org/favicon-32x32.png?v=8944a05a8b601855de116c8a56d3b3ae — 200 — 1.2 KiB — 3 ms — h2https://www.typescriptlang.org/icons/icon-144x144.png?v=8944a05a8b601855de116c8a56d3b3aewww.typescriptlang.org/icons/icon-1... https://www.typescriptlang.org/icons/icon-144x144.png?v=8944a05a8b601855de116c8a56d3b3ae — 200 — 4.6 KiB — 3 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
77% of JavaScript execution is third-party
First-party Third-party 197ms · 142KB · $1/mo
www.typescriptlang.org
Other
Optional
Execution 127ms
Transfer 69 KB
Monthly Cost $0/mo
www.typescriptlang.org
Other
Optional
Execution 70ms
Transfer 73 KB
Unused 38%
Monthly Cost $0/mo

77% 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

Image Optimization
3 images, 16 KB total, 0 KB wasted
INFO

Image Optimization Audit

Total Images

3

Total Size

16 KB

2 missing dimensions 3 missing lazy loading
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

Send Feedback