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https://www.sublimetext.com

Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
95
GRADE
A
FIX
1
REVIEW
2
PASS
9
INFO
2

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

Mobile Desktop
100
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.

244 ms

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

284 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.

0.000

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

1.13 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.

284 ms

Page Load Progression

413 ms
826 ms
1.2 s
1.7 s
2.1 s
2.5 s
2.9 s
3.3 s
Checks
14
9 PASS 2 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
17 images, 0 KB saveable
REVIEW
17 images, 0 KB saveable
Warning::
https://www.sublimetext.com/images/icon_gpu.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.sublimetext.com/images/icon_arm64.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.sublimetext.com/images/icon_python.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.sublimetext.com/images/icon_auto_compl... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.sublimetext.com/images/icon_ts.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.sublimetext.com/images/icon_dark_mode.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.sublimetext.com/images/icon_tab_multi.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://www.sublimetext.com/images/icon_syntax.svg is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
17 images 396 KB
0 oversized -0 KB
16 legacy format
8 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

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
517 KB transferred, 24 requests
PASS
517 KB transferred, 24 requests
Info::
Page weighs 588 KB (517 KB transferred)
Info::
24 HTTP requests
Info::
Estimated 0.11 g CO2 per page load
517 KB / 2.4 MB budget
517 KB transferred
24 requests
0.11 g CO2 per page load
Images 396.0 KiB 77%
Fonts 70.0 KiB 14%
Other 26.6 KiB 5%
CSS 9.1 KiB 2%
HTML 8.9 KiB 2%
JavaScript 6.0 KiB 1%
0 2.4 MB 4.9 MB
Under budget
A+
Third-Party Impact
15% third-party, 0 ms blocking
PASS
15% third-party, 0 ms blocking
Info::
Third-party code accounts for 15% of page weight (76.0 KiB of 516.6 KiB)
Info::
Third-party blocking time is low (0 ms)
85%
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
148ms total JS execution
PASS
148ms total JS execution
Info::
https://www.sublimetext.com/: 95ms CPU time
Info::
Unattributable: 53ms CPU time
Info::
Third-party scripts: 53ms (36% of total)

Main Thread Breakdown

Other 55% Style & Layout 26% Script Evaluation 9% Rendering 7%
ScriptTotalScriptingParse/CompileParty
https://www.sublimetext.com/95ms12ms1ms1st
Unattributable53ms1ms0ms3rd
A+
Font Loading
3 fonts (70 KB)
PASS
3 fonts (70 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

70 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 244 ms LCP 284 mshttps://www.sublimetext.com/fonts/lato-v16-latin-regular.woff2lato-v16-latin-regular.... https://www.sublimetext.com/fonts/lato-v16-latin-regular.woff2 — 23.2 KiB — 0 ms — font-display: swaphttps://www.sublimetext.com/fonts/lato-v16-latin-700.woff2lato-v16-latin-700.woff2 https://www.sublimetext.com/fonts/lato-v16-latin-700.woff2 — 22.7 KiB — 0 ms — font-display: swaphttps://www.sublimetext.com/fonts/lato-v16-latin-italic.woff2lato-v16-latin-italic.w... https://www.sublimetext.com/fonts/lato-v16-latin-italic.woff2 — 24.1 KiB — 0 ms — font-display: swap
lato-v16-latin-regular.... woff2 swap
Size 23 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
lato-v16-latin-700.woff2 woff2 swap
Size 23 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
lato-v16-latin-italic.w... woff2 swap
Size 24 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)
A+
JS Bundles
1 scripts, 0 KB unused
PASS
1 scripts, 0 KB unused
0 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.sublimetext.com/screencasts/osx_dark.js?v26 KB—✓1st
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
Network Waterfall
24 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
36% of JavaScript execution is third-party
First-party Third-party 53ms · 0KB · $1/mo
Unattributable
Other
Optional
Execution 53ms
Transfer 0 KB
Monthly Cost $1/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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