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Performance

· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
95
GRADE
A
FIX
1
REVIEW
3
PASS
9
INFO
2

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

Mobile Desktop
98
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
96
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
96
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.

526 ms

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

874 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.

0.077

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

526 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.

878 ms

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
15
9 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::
ETag present — enables conditional (304) responses

No Cache-Control header

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

C
Image Optimization
Action
11 images, 0 KB saveable
REVIEW
11 images, 0 KB saveable
Warning::
https://pypi-camo.freetls.fastly.net/8855f7c063a3b... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://pypi-camo.freetls.fastly.net/df6fe8829cbff... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://pypi-camo.freetls.fastly.net/d01053c02f3a6... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://pypi-camo.freetls.fastly.net/b611884ff9043... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://pypi.org/static/images/logo-large.516e776d... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://pypi-camo.freetls.fastly.net/60f709d24f3e4... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://pypi-camo.freetls.fastly.net/420cc8cf360ba... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://pypi-camo.freetls.fastly.net/67af7117035e2... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://pypi.org/static/images/logo-small.8998e9d1... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://pypi.org/static/images/white-cube.2351a86c... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://pypi-camo.freetls.fastly.net/ed7074cadad1a... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
11 images 88 KB
0 oversized -0 KB
11 legacy format
11 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

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
3 scripts, 66 KB unused
REVIEW
3 scripts, 66 KB unused
Warning::
https://pypi.org/static/js/warehouse.e9abdc3b.js: 66 KB unused (63%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 66 KB
66 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://pypi.org/static/js/warehouse.e9abdc3b.js105 KB66 KB (63%)✓1st
https://analytics.python.org/js/script.js2 KB—✓3rd
https://media.ethicalads.io/media/client/v1.4.0/ethicalads.min.js9 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

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

Green Hosting

No green hosting detected

A+
Page Weight Budget
556 KB transferred, 28 requests
PASS
556 KB transferred, 28 requests
Info::
Page weighs 580 KB (556 KB transferred)
Info::
28 HTTP requests
Info::
Estimated 0.11 g CO2 per page load
556 KB / 2.4 MB budget
556 KB transferred
28 requests
0.11 g CO2 per page load
CSS 174.8 KiB 31%
Fonts 161.5 KiB 29%
JavaScript 115.5 KiB 21%
Images 87.6 KiB 16%
HTML 6.8 KiB 1%
Other 6.1 KiB 1%
Other 4.2 KiB 1%
0 2.4 MB 4.9 MB
Under budget
A+
Third-Party Impact
6% third-party, 0 ms blocking
PASS
6% third-party, 0 ms blocking
Info::
Third-party code accounts for 6% of page weight (32.0 KiB of 556.4 KiB)
Info::
Third-party blocking time is low (0 ms)
94%
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
149ms total JS execution
PASS
149ms total JS execution
Info::
https://pypi.org/: 90ms CPU time
Info::
Unattributable: 60ms CPU time
Info::
Third-party scripts: 60ms (40% of total)

Main Thread Breakdown

Style & Layout 40% Other 30% Script Evaluation 19% Rendering 5% Parse HTML & CSS 3%
ScriptTotalScriptingParse/CompileParty
https://pypi.org/90ms2ms0ms1st
Unattributable60ms2ms0ms3rd
A+
Font Loading
5 fonts (162 KB)
PASS
5 fonts (162 KB)
Info::
5 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

5

162 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 526 ms LCP 874 mshttps://pypi.org/static/webfonts/source-sans-3-latin-400-normal.5e0fb0b8.woff2source-sans-3-latin-400... https://pypi.org/static/webfonts/source-sans-3-latin-400-normal.5e0fb0b8.woff2 — 15.5 KiB — 23 ms — font-display: swaphttps://pypi.org/static/webfonts/source-sans-3-latin-600-normal.7dc998af.woff2source-sans-3-latin-600... https://pypi.org/static/webfonts/source-sans-3-latin-600-normal.7dc998af.woff2 — 15.5 KiB — 23 ms — font-display: swaphttps://pypi.org/static/webfonts/fa-solid-900.ce9a3fa7.woff2fa-solid-900.ce9a3fa7.w... https://pypi.org/static/webfonts/fa-solid-900.ce9a3fa7.woff2 — 112.3 KiB — 47 ms — font-display: swaphttps://pypi.org/static/webfonts/source-sans-3-cyrillic-400-normal.b88e2831.woff2source-sans-3-cyrillic-... https://pypi.org/static/webfonts/source-sans-3-cyrillic-400-normal.b88e2831.woff2 — 10.1 KiB — 10 ms — font-display: swaphttps://pypi.org/static/webfonts/source-sans-3-greek-400-normal.034ea2f2.woff2source-sans-3-greek-400... https://pypi.org/static/webfonts/source-sans-3-greek-400-normal.034ea2f2.woff2 — 8.1 KiB — 10 ms — font-display: swap
source-sans-3-latin-400... woff2 swap
Size 16 KB
Load time 23 ms
Start 133 ms
Risk FOUT — text flashes from fallback to web font
source-sans-3-latin-600... woff2 swap
Size 15 KB
Load time 23 ms
Start 133 ms
Risk FOUT — text flashes from fallback to web font
fa-solid-900.ce9a3fa7.w... woff2 swap
Size 112 KB
Load time 47 ms
Start 134 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
source-sans-3-cyrillic-... woff2 swap
Size 10 KB
Load time 10 ms
Start 138 ms
Risk FOUT — text flashes from fallback to web font
source-sans-3-greek-400... woff2 swap
Size 8 KB
Load time 10 ms
Start 138 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 ~56 KB and ~112 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+
Page Weight Inventory
28 resources · 556 KB · 66 KB savings available
PASS
28 resources · 556 KB · 66 KB savings available
Info::
Within 1MB page-weight target
Got: 556 KB
Info::
~66 KB of savings available
Info::
12 third-party resources (6% of weight)
28 resources · 556.4 KiB · 12 third-party Within 1MB page-weight target
CSS 31% · 174.8 KiB
Font 29% · 161.5 KiB
JavaScript 21% · 115.5 KiB
Image 16% · 91.7 KiB
Document 2% · 11.4 KiB
Other 0% · 1.5 KiB

~66.4 KiB of savings available

Remove unused JavaScript: 66.4 KiB
Network Waterfall
28 requests over 498ms
INFO
0 ms 200 ms 400 ms 600 ms 800 ms FCP 526 ms LCP 874 mshttps://pypi.org// https://pypi.org/ — 200 — 6.8 KiB — 19 ms — h2https://pypi.org/static/css/warehouse-ltr.0f58843e.css/static/css/warehouse-ltr.0f58843e.... https://pypi.org/static/css/warehouse-ltr.0f58843e.css — 200 — 88.5 KiB — 25 ms — h2https://pypi.org/static/css/fontawesome.379f9724.css/static/css/fontawesome.379f9724.cs... https://pypi.org/static/css/fontawesome.379f9724.css — 200 — 68.7 KiB — 22 ms — h2https://pypi.org/static/css/fonts.3b5d1a1c.css/static/css/fonts.3b5d1a1c.css https://pypi.org/static/css/fonts.3b5d1a1c.css — 200 — 17.7 KiB — 20 ms — h2https://pypi.org/static/images/logo-small.8998e9d1.svg/static/images/logo-small.8998e9d1.... https://pypi.org/static/images/logo-small.8998e9d1.svg — 200 — 52.0 KiB — 16 ms — h2https://pypi.org/static/images/white-cube.2351a86c.svg/static/images/white-cube.2351a86c.... https://pypi.org/static/images/white-cube.2351a86c.svg — 200 — 573 B — 20 ms — h2https://pypi.org/static/js/warehouse.e9abdc3b.js/static/js/warehouse.e9abdc3b.js https://pypi.org/static/js/warehouse.e9abdc3b.js — 200 — 105.3 KiB — 14 ms — h2https://analytics.python.org/js/script.jsanalytics.python.org/js/script.js https://analytics.python.org/js/script.js — 200 — 1.5 KiB — 53 ms — h2https://media.ethicalads.io/media/client/v1.4.0/ethicalads.min.jsmedia.ethicalads.io/media/client/v1... https://media.ethicalads.io/media/client/v1.4.0/ethicalads.min.js — 200 — 8.7 KiB — 60 ms — h2https://pypi.org/static/images/logo-large.516e776d.svg/static/images/logo-large.516e776d.... https://pypi.org/static/images/logo-large.516e776d.svg — 200 — 14.6 KiB — 10 ms — h2https://pypi-camo.freetls.fastly.net/ed7074cadad1a06f56bc520ad9bd3e00d0704c5b/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f6177732d77686974652d6c6f676f2d7443615473387a432e706e67pypi-camo.freetls.fastly.net/ed7074... https://pypi-camo.freetls.fastly.net/ed7074cadad1a06f56bc520ad9bd3e00d0704c5b/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f6177732d77686974652d6c6f676f2d7443615473387a432e706e67 — 200 — 2.1 KiB — 50 ms — h2https://pypi-camo.freetls.fastly.net/8855f7c063a3bdb5b0ce8d91bfc50cf851cc5c51/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f64617461646f672d77686974652d6c6f676f2d6668644c4e666c6f2e706e67pypi-camo.freetls.fastly.net/8855f7... https://pypi-camo.freetls.fastly.net/8855f7c063a3bdb5b0ce8d91bfc50cf851cc5c51/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f64617461646f672d77686974652d6c6f676f2d6668644c4e666c6f2e706e67 — 200 — 2.5 KiB — 50 ms — h2https://pypi-camo.freetls.fastly.net/60f709d24f3e4d469f9adc77c65e2f5291a3d165/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f6465706f742d77686974652d6c6f676f2d7038506f476831302e706e67pypi-camo.freetls.fastly.net/60f709... https://pypi-camo.freetls.fastly.net/60f709d24f3e4d469f9adc77c65e2f5291a3d165/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f6465706f742d77686974652d6c6f676f2d7038506f476831302e706e67 — 200 — 3.3 KiB — 50 ms — h2https://pypi-camo.freetls.fastly.net/df6fe8829cbff2d7f668d98571df1fd011f36192/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f666173746c792d77686974652d6c6f676f2d65684d3077735f6f2e706e67pypi-camo.freetls.fastly.net/df6fe8... https://pypi-camo.freetls.fastly.net/df6fe8829cbff2d7f668d98571df1fd011f36192/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f666173746c792d77686974652d6c6f676f2d65684d3077735f6f2e706e67 — 200 — 1.5 KiB — 49 ms — h2https://pypi-camo.freetls.fastly.net/420cc8cf360bac879e24c923b2f50ba7d1314fb0/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f676f6f676c652d77686974652d6c6f676f2d616734424e3774332e706e67pypi-camo.freetls.fastly.net/420cc8... https://pypi-camo.freetls.fastly.net/420cc8cf360bac879e24c923b2f50ba7d1314fb0/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f676f6f676c652d77686974652d6c6f676f2d616734424e3774332e706e67 — 200 — 1.9 KiB — 48 ms — h2https://pypi-camo.freetls.fastly.net/d01053c02f3a626b73ffcb06b96367fdbbf9e230/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f70696e67646f6d2d77686974652d6c6f676f2d67355831547546362e706e67pypi-camo.freetls.fastly.net/d01053... https://pypi-camo.freetls.fastly.net/d01053c02f3a626b73ffcb06b96367fdbbf9e230/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f70696e67646f6d2d77686974652d6c6f676f2d67355831547546362e706e67 — 200 — 1.7 KiB — 48 ms — h2https://pypi.org/static/webfonts/source-sans-3-latin-400-normal.5e0fb0b8.woff2/static/webfonts/source-sans-3-lati... https://pypi.org/static/webfonts/source-sans-3-latin-400-normal.5e0fb0b8.woff2 — 200 — 15.5 KiB — 23 ms — h2https://pypi.org/static/webfonts/source-sans-3-latin-600-normal.7dc998af.woff2/static/webfonts/source-sans-3-lati... https://pypi.org/static/webfonts/source-sans-3-latin-600-normal.7dc998af.woff2 — 200 — 15.5 KiB — 23 ms — h2https://pypi.org/static/webfonts/fa-solid-900.ce9a3fa7.woff2/static/webfonts/fa-solid-900.ce9a3... https://pypi.org/static/webfonts/fa-solid-900.ce9a3fa7.woff2 — 200 — 112.3 KiB — 47 ms — h2https://pypi.org/static/webfonts/source-sans-3-cyrillic-400-normal.b88e2831.woff2/static/webfonts/source-sans-3-cyri... https://pypi.org/static/webfonts/source-sans-3-cyrillic-400-normal.b88e2831.woff2 — 200 — 10.1 KiB — 10 ms — h2https://pypi.org/static/webfonts/source-sans-3-greek-400-normal.034ea2f2.woff2/static/webfonts/source-sans-3-gree... https://pypi.org/static/webfonts/source-sans-3-greek-400-normal.034ea2f2.woff2 — 200 — 8.1 KiB — 10 ms — h2https://pypi.org/_includes/unauthed/notification-banners//_includes/unauthed/notification-ba... https://pypi.org/_includes/unauthed/notification-banners/ — 200 — 2.7 KiB — 20 ms — h2https://pypi.org/_includes/unauthed/flash-messages//_includes/unauthed/flash-messages/ https://pypi.org/_includes/unauthed/flash-messages/ — 200 — 1.9 KiB — 354 ms — h2https://2p66nmmycsj3.statuspage.io/api/v2/status.json2p66nmmycsj3.statuspage.io/api/v2/s... https://2p66nmmycsj3.statuspage.io/api/v2/status.json — 200 — 1.2 KiB — 43 ms — h2https://pypi-camo.freetls.fastly.net/67af7117035e2345bacb5a82e9aa8b5b3e70701d/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f73656e7472792d77686974652d6c6f676f2d4a2d6b64742d706e2e706e67pypi-camo.freetls.fastly.net/67af71... https://pypi-camo.freetls.fastly.net/67af7117035e2345bacb5a82e9aa8b5b3e70701d/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f73656e7472792d77686974652d6c6f676f2d4a2d6b64742d706e2e706e67 — 200 — 5.2 KiB — 6 ms — h2https://pypi-camo.freetls.fastly.net/b611884ff90435a0575dbab7d9b0d3e60f136466/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f737461747573706167652d77686974652d6c6f676f2d5467476c6a4a2d502e706e67pypi-camo.freetls.fastly.net/b61188... https://pypi-camo.freetls.fastly.net/b611884ff90435a0575dbab7d9b0d3e60f136466/68747470733a2f2f73746f726167652e676f6f676c65617069732e636f6d2f707970692d6173736574732f73706f6e736f726c6f676f732f737461747573706167652d77686974652d6c6f676f2d5467476c6a4a2d502e706e67 — 200 — 2.2 KiB — 7 ms — h2https://analytics.python.org/api/eventanalytics.python.org/api/event https://analytics.python.org/api/event — 202 — 292 B — 108 ms — h3https://pypi.org/static/images/favicon.35549fe8.ico/static/images/favicon.35549fe8.ico https://pypi.org/static/images/favicon.35549fe8.ico — 200 — 4.2 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
40% of JavaScript execution is third-party
First-party Third-party 60ms · 0KB · €1/mo
Unattributable
Other
Optional
Execution 60ms
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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