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
33 images, 0 KB saveable
REVIEW
33 images, 0 KB saveable
Warning::
!
https://www.guinnessworldrecords.com/images/og_ima... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/products/imag... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/products/imag... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/products/imag... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/images/gwr-st... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/images/guinne... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/news/2026/4/i... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/images/marath... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/images/logo.p... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/images/london... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/news/2026/4/i... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/news/2026/4/i... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/news/2026/4/i... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/products/imag... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/news/2026/4/i... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/news/2026/4/i... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/images/employ... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/images/dr-how... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.guinnessworldrecords.com/news/2026/4/i... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
33images3.2 MB
0oversized-0 KB
29legacy format
19missing dimensionsCLS 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
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
3 fonts (84 KB)
PASS
3 fonts (84 KB)
Info::
i
3 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
3
84 KB total
Render-blocking
0
of 3
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
rubik-regular-webfont.w...woff2swap
Size27 KB
Load time102 ms
Start183 ms
RiskFOUT — text flashes from fallback to web font
gwr.ttfttfswap
Size29 KB
Load time100 ms
Start183 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
rubik-medium-webfont.woff2woff2swap
Size28 KB
Load time65 ms
Start184 ms
RiskFOUT — 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 ~9 KB and ~18 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
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
143 requests over 4361ms
INFO
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
100%of JavaScript execution is third-party
First-party Third-party6846ms · 1926KB · €74/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
Unattributable
Unattributable
Other
794ms
0 KB
—
€9/mo
Costly
www.guinnessworldrecords.com
www.guinnessworldrecords.com
Other
501ms
8 KB
—
€5/mo
Costly
tagan.adlightning.com
tagan.adlightning.com
Other
448ms
15 KB
—
€5/mo
Costly
sdks.shopifycdn.com
sdks.shopifycdn.com
Other
446ms
60 KB
45%
€5/mo
Costly
www.ezojs.com
www.ezojs.com
Other
383ms
15 KB
—
€4/mo
Costly
client.aps.amazon-adsystem.com
client.aps.amazon-adsystem.com
Other
299ms
82 KB
—
€3/mo
Costly
go.ezodn.com
go.ezodn.com
Other
294ms
66 KB
75%
€3/mo
Costly
securepubads.g.doubleclick.net
securepubads.g.doubleclick.net
Other
277ms
187 KB
70%
€3/mo
Costly
the.gatekeeperconsent.com
the.gatekeeperconsent.com
Other
254ms
26 KB
—
€3/mo
Costly
go.ezodn.com
go.ezodn.com
Other
254ms
236 KB
74%
€3/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
249ms
148 KB
45%
€3/mo
Costly
www.guinnessworldrecords.com
www.guinnessworldrecords.com
Other
231ms
30 KB
—
€3/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
218ms
168 KB
36%
€2/mo
Costly
tagan.adlightning.com
tagan.adlightning.com
Other
203ms
32 KB
—
€2/mo
Costly
www.guinnessworldrecords.com
www.guinnessworldrecords.com
Other
181ms
2 KB
—
€2/mo
Optional
www.ezojs.com
www.ezojs.com
Other
170ms
102 KB
57%
€2/mo
Optional
www.ezojs.com
www.ezojs.com
Other
140ms
66 KB
50%
€2/mo
Optional
www.guinnessworldrecords.com
www.guinnessworldrecords.com
Other
138ms
33 KB
61%
€2/mo
Optional
tagan.adlightning.com
tagan.adlightning.com
Other
136ms
70 KB
—
€1/mo
Optional
go.ezodn.com
go.ezodn.com
Other
131ms
96 KB
57%
€1/mo
Optional
config.aps.amazon-adsystem.com
config.aps.amazon-adsystem.com
Other
117ms
3 KB
—
€1/mo
Optional
secure.cdn.fastclick.net
secure.cdn.fastclick.net
Other
116ms
22 KB
—
€1/mo
Optional
go.ezodn.com
go.ezodn.com
Other
106ms
63 KB
64%
€1/mo
Optional
Facebook Pixel
connect.facebook.net
Advertising
102ms
97 KB
36%
€1/mo
Optional
Facebook Pixel
connect.facebook.net
Advertising
96ms
44 KB
—
€1/mo
Optional
cdn.id5-sync.com
cdn.id5-sync.com
Other
94ms
35 KB
91%
€1/mo
Optional
Google Analytics
www.google-analytics.com
Analytics
93ms
21 KB
—
€1/mo
Optional
go.ezodn.com
go.ezodn.com
Other
83ms
74 KB
63%
€1/mo
Optional
secure.cdn.fastclick.net
secure.cdn.fastclick.net
Other
80ms
47 KB
—
€1/mo
Optional
securepubads.g.doubleclick.net
securepubads.g.doubleclick.net
Other
79ms
34 KB
—
€1/mo
Optional
LinkedIn Insight
snap.licdn.com
Advertising
68ms
19 KB
—
€1/mo
Optional
secure.cdn.fastclick.net
secure.cdn.fastclick.net
Other
63ms
25 KB
—
€1/mo
Optional
Unattributable
Other
Costly
Execution794ms
Transfer0 KB
Monthly Cost€9/mo
www.guinnessworldrecords.com
Other
Costly
Execution501ms
Transfer8 KB
Monthly Cost€5/mo
tagan.adlightning.com
Other
Costly
Execution448ms
Transfer15 KB
Monthly Cost€5/mo
sdks.shopifycdn.com
Other
Costly
Execution446ms
Transfer60 KB
Unused45%
Monthly Cost€5/mo
www.ezojs.com
Other
Costly
Execution383ms
Transfer15 KB
Monthly Cost€4/mo
client.aps.amazon-adsystem.com
Other
Costly
Execution299ms
Transfer82 KB
Monthly Cost€3/mo
go.ezodn.com
Other
Costly
Execution294ms
Transfer66 KB
Unused75%
Monthly Cost€3/mo
securepubads.g.doubleclick.net
Other
Costly
Execution277ms
Transfer187 KB
Unused70%
Monthly Cost€3/mo
the.gatekeeperconsent.com
Other
Costly
Execution254ms
Transfer26 KB
Monthly Cost€3/mo
go.ezodn.com
Other
Costly
Execution254ms
Transfer236 KB
Unused74%
Monthly Cost€3/mo
Google Tag Manager
Tag Manager
Costly
Execution249ms
Transfer148 KB
Unused45%
Monthly Cost€3/mo
www.guinnessworldrecords.com
Other
Costly
Execution231ms
Transfer30 KB
Monthly Cost€3/mo
Google Tag Manager
Tag Manager
Costly
Execution218ms
Transfer168 KB
Unused36%
Monthly Cost€2/mo
tagan.adlightning.com
Other
Costly
Execution203ms
Transfer32 KB
Monthly Cost€2/mo
www.guinnessworldrecords.com
Other
Optional
Execution181ms
Transfer2 KB
Monthly Cost€2/mo
www.ezojs.com
Other
Optional
Execution170ms
Transfer102 KB
Unused57%
Monthly Cost€2/mo
www.ezojs.com
Other
Optional
Execution140ms
Transfer66 KB
Unused50%
Monthly Cost€2/mo
www.guinnessworldrecords.com
Other
Optional
Execution138ms
Transfer33 KB
Unused61%
Monthly Cost€2/mo
tagan.adlightning.com
Other
Optional
Execution136ms
Transfer70 KB
Monthly Cost€1/mo
go.ezodn.com
Other
Optional
Execution131ms
Transfer96 KB
Unused57%
Monthly Cost€1/mo
config.aps.amazon-adsystem.com
Other
Optional
Execution117ms
Transfer3 KB
Monthly Cost€1/mo
secure.cdn.fastclick.net
Other
Optional
Execution116ms
Transfer22 KB
Monthly Cost€1/mo
go.ezodn.com
Other
Optional
Execution106ms
Transfer63 KB
Unused64%
Monthly Cost€1/mo
Facebook Pixel
Advertising
Optional
Execution102ms
Transfer97 KB
Unused36%
Monthly Cost€1/mo
Facebook Pixel
Advertising
Optional
Execution96ms
Transfer44 KB
Monthly Cost€1/mo
cdn.id5-sync.com
Other
Optional
Execution94ms
Transfer35 KB
Unused91%
Monthly Cost€1/mo
Google Analytics
Analytics
Optional
Execution93ms
Transfer21 KB
Monthly Cost€1/mo
go.ezodn.com
Other
Optional
Execution83ms
Transfer74 KB
Unused63%
Monthly Cost€1/mo
secure.cdn.fastclick.net
Other
Optional
Execution80ms
Transfer47 KB
Monthly Cost€1/mo
securepubads.g.doubleclick.net
Other
Optional
Execution79ms
Transfer34 KB
Monthly Cost€1/mo
LinkedIn Insight
Advertising
Optional
Execution68ms
Transfer19 KB
Monthly Cost€1/mo
secure.cdn.fastclick.net
Other
Optional
Execution63ms
Transfer25 KB
Monthly Cost€1/mo
These scripts may cost more than they're worth
Unattributable adds 794ms and costs ~€9/month
www.guinnessworldrecords.com adds 501ms and costs ~€5/month
tagan.adlightning.com adds 448ms and costs ~€5/month
sdks.shopifycdn.com adds 446ms and costs ~€5/month
www.ezojs.com adds 383ms and costs ~€4/month
client.aps.amazon-adsystem.com adds 299ms and costs ~€3/month
go.ezodn.com adds 294ms and costs ~€3/month
securepubads.g.doubleclick.net adds 277ms and costs ~€3/month
the.gatekeeperconsent.com adds 254ms and costs ~€3/month
go.ezodn.com adds 254ms and costs ~€3/month
Google Tag Manager adds 249ms and costs ~€3/month
www.guinnessworldrecords.com adds 231ms and costs ~€3/month
Google Tag Manager adds 218ms and costs ~€2/month
tagan.adlightning.com adds 203ms and costs ~€2/month
100% 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
Unattributable takes 794ms 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
www.guinnessworldrecords.com takes 501ms 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
tagan.adlightning.com takes 448ms 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
sdks.shopifycdn.com takes 446ms 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
www.ezojs.com takes 383ms 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
client.aps.amazon-adsystem.com takes 299ms 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
go.ezodn.com takes 294ms 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
75% of go.ezodn.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
securepubads.g.doubleclick.net takes 277ms 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 securepubads.g.doubleclick.net'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
the.gatekeeperconsent.com takes 254ms 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
go.ezodn.com takes 254ms 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
74% of go.ezodn.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
Google Tag Manager takes 249ms 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
www.guinnessworldrecords.com takes 231ms 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
Google Tag Manager takes 218ms 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
tagan.adlightning.com takes 203ms 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
57% of www.ezojs.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
61% of www.guinnessworldrecords.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
57% of go.ezodn.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
64% of go.ezodn.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
91% of cdn.id5-sync.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
63% of go.ezodn.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.