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
45 images, 0 KB saveable
REVIEW
45 images, 0 KB saveable
Warning::
!
https://www.phoca.cz//images/projects/phoca-panora... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-galler... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-comman... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-instal... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-cart-r... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz/images/ecommerce/phoca-cart-w... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz/images/blog/phoca-ai.jpg#joom... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-photo-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-pdf-r.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-maps-r... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-favico... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz/images/article/phoca-cart-shi... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-restau... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-sef-r.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz/images/phoca-seal.png is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-guestb... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-docume... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-font-r... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-email-... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.phoca.cz//images/projects/phoca-downlo... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
45images839 KB
0oversized-0 KB
24legacy format
20missing 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
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
9 fonts (591 KB)
PASS
9 fonts (591 KB)
Info::
i
9 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
9
591 KB total
Render-blocking
0
of 9
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
inter-v13-latin_latin-e...woff2swap
Size44 KB
Load time313 ms
Start733 ms
RiskFOUT — text flashes from fallback to web font
inter-v13-latin_latin-e...woff2swap
Size47 KB
Load time317 ms
Start733 ms
RiskFOUT — text flashes from fallback to web font
inter-v13-latin_latin-e...woff2swap
Size46 KB
Load time339 ms
Start734 ms
RiskFOUT — text flashes from fallback to web font
fa-brands-400.woff2woff2swap
Size0 KB
Load time65 ms
Start1.1 s
RiskFOUT — text flashes from fallback to web font
fa-solid-900.woff2woff2swap
Size155 KB
Load time252 ms
Start1.1 s
RiskFOUT — 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
fa-brands-400.ttfttfswap
Size206 KB
Load time267 ms
Start1.2 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
Subset this font — over 100 KB suggests Latin Extended or full glyph coverage that most pages don't need
memvYaGs126MiZpBA-UvWbX...woff2swap
Size42 KB
Load time76 ms
Start1.2 s
RiskFOUT — text flashes from fallback to web font
KFOMCnqEu92Fr1ME7kSn66a...woff2swap
Size15 KB
Load time63 ms
Start1.2 s
RiskFOUT — text flashes from fallback to web font
KFO7CnqEu92Fr1ME7kSn66a...woff2swap
Size37 KB
Load time26 ms
Start1.5 s
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 ~242 KB and ~484 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+
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
92 requests over 2458ms
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-party2013ms · 594KB · Kč248/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
pagead2.googlesyndication.com
pagead2.googlesyndication.com
Other
482ms
55 KB
79%
Kč59/mo
Costly
Unattributable
Unattributable
Other
351ms
0 KB
—
Kč43/mo
Costly
www.phoca.cz
www.phoca.cz
Other
300ms
66 KB
—
Kč37/mo
Costly
fundingchoicesmessages.google.com
fundingchoicesmessages.google.com
Other
256ms
68 KB
—
Kč32/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
196ms
154 KB
41%
Kč24/mo
Optional
fundingchoicesmessages.google.com
fundingchoicesmessages.google.com
Other
177ms
70 KB
52%
Kč22/mo
Optional
pagead2.googlesyndication.com
pagead2.googlesyndication.com
Other
161ms
178 KB
83%
Kč20/mo
Optional
cse.google.com
cse.google.com
Other
90ms
4 KB
—
Kč11/mo
Optional
pagead2.googlesyndication.com
Other
Costly
Execution482ms
Transfer55 KB
Unused79%
Monthly CostKč59/mo
Unattributable
Other
Costly
Execution351ms
Transfer0 KB
Monthly CostKč43/mo
www.phoca.cz
Other
Costly
Execution300ms
Transfer66 KB
Monthly CostKč37/mo
fundingchoicesmessages.google.com
Other
Costly
Execution256ms
Transfer68 KB
Monthly CostKč32/mo
Google Tag Manager
Tag Manager
Optional
Execution196ms
Transfer154 KB
Unused41%
Monthly CostKč24/mo
fundingchoicesmessages.google.com
Other
Optional
Execution177ms
Transfer70 KB
Unused52%
Monthly CostKč22/mo
pagead2.googlesyndication.com
Other
Optional
Execution161ms
Transfer178 KB
Unused83%
Monthly CostKč20/mo
cse.google.com
Other
Optional
Execution90ms
Transfer4 KB
Monthly CostKč11/mo
These scripts may cost more than they're worth
pagead2.googlesyndication.com adds 482ms and costs ~Kč59/month
Unattributable adds 351ms and costs ~Kč43/month
www.phoca.cz adds 300ms and costs ~Kč37/month
fundingchoicesmessages.google.com adds 256ms and costs ~Kč32/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
pagead2.googlesyndication.com takes 482ms 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
79% 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
Unattributable takes 351ms 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.phoca.cz takes 300ms 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
fundingchoicesmessages.google.com takes 256ms 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
52% of fundingchoicesmessages.google.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
83% 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.