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
37 images, 0 KB saveable
REVIEW
37 images, 0 KB saveable
Warning::
!
https://www.uoa.gr/fileadmin/user_upload/Banners/c... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/uploads/pics/masonry_... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/user_upload/PDF-files... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/user_upload/template_... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/uploads/pics/masonry6... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/uploads/pics/ERASMUS2... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/uploads/pics/uoa_vide... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/uploads/pics/civis-54... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/uploads/pics/masonry5... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/uploads/pics/research... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/uploads/pics/BAAG_259... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/uploads/pics/research... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.uoa.gr/fileadmin/uploads/pics/medicen.... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
37images3.8 MB
0oversized-0 KB
37legacy format
13missing 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
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 (444 KB)
PASS
9 fonts (444 KB)
Info::
i
9 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
9
444 KB total
Render-blocking
0
of 9
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
memvYaGs126MiZpBA-UvWbX...woff2swap
Size42 KB
Load time47 ms
Start2.7 s
RiskFOUT — text flashes from fallback to web font
GFSDidotBold.woffwoffswap
Size73 KB
Load time399 ms
Start2.7 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
fontawesome-webfont.woff2woff2swap
Size65 KB
Load time399 ms
Start2.7 s
RiskFOUT — text flashes from fallback to web font
KFO7CnqEu92Fr1ME7kSn66a...woff2swap
Size37 KB
Load time18 ms
Start2.7 s
RiskFOUT — text flashes from fallback to web font
fa-brands-400.woff2woff2swap
Size115 KB
Load time407 ms
Start2.7 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
memvYaGs126MiZpBA-UvWbX...woff2swap
Size46 KB
Load time39 ms
Start2.7 s
RiskFOUT — text flashes from fallback to web font
memvYaGs126MiZpBA-UvWbX...woff2swap
Size17 KB
Load time33 ms
Start2.7 s
RiskFOUT — text flashes from fallback to web font
KFO7CnqEu92Fr1ME7kSn66a...woff2swap
Size35 KB
Load time29 ms
Start2.7 s
RiskFOUT — text flashes from fallback to web font
KFO7CnqEu92Fr1ME7kSn66a...woff2swap
Size14 KB
Load time24 ms
Start2.7 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 ~79 KB and ~158 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
71 requests over 4318ms
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-party2882ms · 446KB · €31/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
www.uoa.gr
www.uoa.gr
Other
1177ms
21 KB
—
€13/mo
Costly
www.uoa.gr
www.uoa.gr
Other
686ms
215 KB
77%
€7/mo
Costly
Unattributable
Unattributable
Other
498ms
0 KB
—
€5/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
379ms
157 KB
42%
€4/mo
Costly
www.uoa.gr
www.uoa.gr
Other
143ms
53 KB
—
€2/mo
Optional
www.uoa.gr
Other
Costly
Execution1177ms
Transfer21 KB
Monthly Cost€13/mo
www.uoa.gr
Other
Costly
Execution686ms
Transfer215 KB
Unused77%
Monthly Cost€7/mo
Unattributable
Other
Costly
Execution498ms
Transfer0 KB
Monthly Cost€5/mo
Google Tag Manager
Tag Manager
Costly
Execution379ms
Transfer157 KB
Unused42%
Monthly Cost€4/mo
www.uoa.gr
Other
Optional
Execution143ms
Transfer53 KB
Monthly Cost€2/mo
These scripts may cost more than they're worth
www.uoa.gr adds 1177ms and costs ~€13/month
www.uoa.gr adds 686ms and costs ~€7/month
Unattributable adds 498ms and costs ~€5/month
Google Tag Manager adds 379ms and costs ~€4/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
www.uoa.gr takes 1177ms 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.uoa.gr takes 686ms 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
77% of www.uoa.gr'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 498ms 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 379ms 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.