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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
82
GRADE
B
FIX
2
REVIEW
5
PASS
5
INFO
2

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.
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.

657 ms

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

1.21 s

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

4 ms

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

0.058

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

1.01 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.

1.66 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
5 PASS 5 REVIEW 2 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
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 589.8 KiB 41%
Images 567.2 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 908 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/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/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/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/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/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/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/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/lw630/nature-cms/... 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.
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

B
JS Execution Cost
536ms total JS execution
REVIEW
536ms total JS execution
Info::
https://sgtm.nature.com/gtm.js?id=GTM-MRVXSHQ: 172ms CPU time
Info::
https://www.nature.com/: 117ms CPU time
Info::
Unattributable: 94ms CPU time
Info::
https://pagead2.googlesyndication.com/pagead/manag...: 82ms CPU time
Info::
https://cmp.nature.com/production_live/en/consent-...: 70ms CPU time
Warning::
Third-party scripts: 419ms (78% of total)

Main Thread Breakdown

Script Evaluation 52% Style & Layout 17% Other 16% Script Parsing & Compilation 9%
ScriptTotalScriptingParse/CompileParty
https://sgtm.nature.com/gtm.js?id=GTM-MRVXSHQ172ms150ms17ms3rd
https://www.nature.com/117ms4ms2ms1st
Unattributable94ms2ms0ms3rd
https://pagead2.googlesyndication.com/pagead/managed/js/gpt/m202604030101/pubads_impl.js?cb=3109768082ms65ms16ms3rd
https://cmp.nature.com/production_live/en/consent-bundle-8-102.js70ms49ms4ms3rd
C
JS Bundles
Action
8 scripts, 213 KB unused
REVIEW
8 scripts, 213 KB unused
Warning::
https://pagead2.googlesyndication.com/pagead/manag...: 126 KB unused (69%)
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: 213 KB
213 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://pagead2.googlesyndication.com/pagead/managed/js/gpt/m202604030101/pubads_impl.js?cb=31097680183 KB126 KB (69%)✓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 500 ms 1.0 s FCP 657 ms LCP 1.2 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
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
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 419ms · 426KB · €5/mo
sgtm.nature.com
Other
Optional
Execution 172ms
Transfer 198 KB
Unused 34%
Monthly Cost €2/mo
Unattributable
Other
Optional
Execution 94ms
Transfer 0 KB
Monthly Cost €1/mo
pagead2.googlesyndication.com
Other
Optional
Execution 82ms
Transfer 183 KB
Unused 69%
Monthly Cost €1/mo
cmp.nature.com
Other
Optional
Execution 70ms
Transfer 45 KB
Monthly Cost €1/mo

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

69% 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

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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