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Performance

· 16 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
82
GRADE
B
FIX
3
REVIEW
4
PASS
7
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.
100
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.

2.18 s

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

4.94 s

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

593 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.190

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

2.18 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.

10.38 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
7 PASS 4 REVIEW 3 FIX
D
Third-Party Impact
Action
84% third-party, 0 ms blocking
FIX
84% third-party, 0 ms blocking
Warning::
Third-party code accounts for 84% of page weight (1.2 MiB of 1.4 MiB)
Info::
Third-party blocking time is low (0 ms)
16%
84%
First-party Third-party
D
JS Execution Cost
Action
2212ms total JS execution
FIX
2212ms total JS execution
Warning::
https://sgtm.nature.com/gtm.js?id=GTM-MRVXSHQ: 650ms CPU time
Warning::
https://www.nature.com/: 482ms CPU time
Warning::
Unattributable: 386ms CPU time
Info::
https://pagead2.googlesyndication.com/pagead/manag...: 239ms CPU time
Info::
https://cmp.nature.com/production_live/en/consent-...: 226ms CPU time
Warning::
Third-party scripts: 1729ms (78% of total)

Main Thread Breakdown

Script Evaluation 49% Other 17% Style & Layout 17% Script Parsing & Compilation 10%
ScriptTotalScriptingParse/CompileParty
https://sgtm.nature.com/gtm.js?id=GTM-MRVXSHQ650ms544ms87ms3rd
https://www.nature.com/482ms17ms8ms1st
Unattributable386ms9ms0ms3rd
https://pagead2.googlesyndication.com/pagead/managed/js/gpt/m202604020101/pubads_impl.js239ms180ms57ms3rd
https://cmp.nature.com/production_live/en/consent-bundle-8-102.js226ms156ms16ms3rd
https://scripts.webcontentassessor.com/scripts/93dabb8d80079a87fec7bb6f67b807fce90e1688f8957ad7ad152bfd58ea01c2127ms87ms40ms3rd
https://pagead2.googlesyndication.com/tag/js/gpt.js102ms83ms17ms3rd
D
HTTP Caching
Action
no-store (uncacheable)
FIX
no-store (uncacheable)
Info::
Cache-Control: no-store prevents all caching
Intentional for dynamic content, but increases server load for every page view.
Got: private,must-revalidate,max-age=0,no-store
Info::
No ETag or Last-Modified header
Conditional requests (304 Not Modified) are not possible without validators.
Cache-Control

private,must-revalidate,max-age=0,no-store

DirectiveValueMeaning
private—Only browser cache, not CDN/proxy
must-revalidate—Must recheck with server after expiry
max-age0Cache for 0 seconds
no-store—Never cache this response
B
Page Weight Budget
1.4 MB transferred, 55 requests
REVIEW
1.4 MB transferred, 55 requests
Info::
Page weighs 3.5 MB (1.4 MB transferred)
Warning::
JavaScript is 590 KB — consider code splitting or lazy loading
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
Got: 590 KB
Info::
55 HTTP requests
Info::
Estimated 0.29 g CO2 per page load
1.4 MB / 2.4 MB budget
1.4 MB transferred
55 requests
0.29 g CO2 per page load
JavaScript 589.5 KiB 41%
Images 566.5 KiB 39%
Fonts 137.3 KiB 10%
HTML 50.4 KiB 4%
Other 38.3 KiB 3%
Other 27.9 KiB 2%
CSS 23.1 KiB 2%
Other 1.2 KiB 0%
Other 909 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

C
Image Optimization
Action
31 images, 0 KB saveable
REVIEW
31 images, 0 KB saveable
Warning::
https://media.springernature.com/w485h264/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/lw630/nature-cms/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/full/nature-cms/u... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w485h264/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/springer... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/springer... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/springer... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/springer... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w440/springer-sta... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/springer... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
https://media.springernature.com/w290h158/magazine... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
31 images 567 KB
0 oversized -0 KB
9 legacy format
22 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

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

C
JS Bundles
Action
8 scripts, 215 KB unused
REVIEW
8 scripts, 215 KB unused
Warning::
https://pagead2.googlesyndication.com/pagead/manag...: 128 KB unused (70%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://sgtm.nature.com/gtm.js?id=GTM-MRVXSHQ: 67 KB unused (34%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://scripts.webcontentassessor.com/scripts/93d...: 20 KB unused (17%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 215 KB
215 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://pagead2.googlesyndication.com/pagead/managed/js/gpt/m202604020101/pubads_impl.js183 KB128 KB (70%)✓3rd
https://sgtm.nature.com/gtm.js?id=GTM-MRVXSHQ198 KB67 KB (34%)✓3rd
https://scripts.webcontentassessor.com/scripts/93dabb8d80079a87fec7bb6f67b807fce90e1688f8957ad7ad152bfd58ea01c2123 KB20 KB (17%)✓3rd
https://verify.nature.com/verify/nature.min.js2 KB—✓3rd
https://cmp.nature.com/production_live/en/consent-bundle-8-102.js45 KB—✓3rd
https://www.nature.com/static/js/journal-homepage-es6-bundle-f21f4cfbb8.js4 KB—✓1st
https://www.googletagmanager.com/gtm.js?id=GTM-MRVXSHQ&gtg_health=10 KB—✓3rd
https://pagead2.googlesyndication.com/tag/js/gpt.js34 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

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

Green Hosting

No green hosting detected

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
2 fonts (137 KB)
PASS
2 fonts (137 KB)
Info::
2 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

2

137 KB total

Render-blocking

0

of 2

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 FCP 2.2 s LCP 4.9 shttps://www.nature.com/static/fonts/HardingText-Regular-Web-cecd90984f.woff2HardingText-Regular-Web... https://www.nature.com/static/fonts/HardingText-Regular-Web-cecd90984f.woff2 — 68.0 KiB — 0 ms — font-display: swaphttps://www.nature.com/static/fonts/HardingText-Bold-Web-c37111391c.woff2HardingText-Bold-Web-c3... https://www.nature.com/static/fonts/HardingText-Bold-Web-c37111391c.woff2 — 69.3 KiB — 0 ms — font-display: swap
HardingText-Regular-Web... woff2 swap
Size 68 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
HardingText-Bold-Web-c3... woff2 swap
Size 69 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+
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
2 hints, 0 missing preconnects
PASS
2 hints, 0 missing preconnects
Info::
Page uses 2 resource hint(s)

Current Resource Hints

preconnect
1
preload
1
dns-prefetch
—
prefetch
—

2 resource hints configured

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
Network Waterfall
55 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
78% of JavaScript execution is third-party
First-party Third-party 1729ms · 583KB · €19/mo
sgtm.nature.com
Other
Costly
Execution 650ms
Transfer 198 KB
Unused 34%
Monthly Cost €7/mo
Unattributable
Other
Costly
Execution 386ms
Transfer 0 KB
Monthly Cost €4/mo
pagead2.googlesyndication.com
Other
Costly
Execution 239ms
Transfer 183 KB
Unused 70%
Monthly Cost €3/mo
cmp.nature.com
Other
Costly
Execution 226ms
Transfer 45 KB
Monthly Cost €2/mo
scripts.webcontentassessor.com
Other
Optional
Execution 127ms
Transfer 123 KB
Unused 17%
Monthly Cost €1/mo
pagead2.googlesyndication.com
Other
Optional
Execution 102ms
Transfer 34 KB
Monthly Cost €1/mo

These scripts may cost more than they're worth

  • sgtm.nature.com adds 650ms and costs ~€7/month
  • Unattributable adds 386ms and costs ~€4/month
  • pagead2.googlesyndication.com adds 239ms and costs ~€3/month
  • cmp.nature.com adds 226ms and costs ~€2/month

78% 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

sgtm.nature.com takes 650ms 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 386ms 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

pagead2.googlesyndication.com takes 239ms 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

70% of pagead2.googlesyndication.com's code is unused. The script may be loading features you don't use.

Why this matters

Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.

Source: web.dev

cmp.nature.com takes 226ms 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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