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
31 images, 0 KB saveable
REVIEW
31 images, 0 KB saveable
Warning::
!
https://www.asu.edu/sites/default/files/2025-10/3f... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2026-04/ho... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2025-09/20... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2026-01/ho... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2026-03/Fu... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2025-10/5u... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2026-04/ho... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2026-04/ho... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2026-03/ho... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2025-10/2e... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2026-04/ho... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.asu.edu/sites/default/files/2026-03/to... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
31images3.4 MB
0oversized-0 KB
18legacy format
12missing 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
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
No web fonts (system fonts)
PASS
No web fonts (system fonts)
Info::
✓
No web fonts loaded — system fonts are fastest
No web fonts loaded — system fonts are optimal.
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
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
Network Waterfall
78 requests over 5329ms
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-party4084ms · 2016KB · €71/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
Google Tag Manager
www.googletagmanager.com
Tag Manager
646ms
172 KB
35%
€11/mo
Costly
Unattributable
Unattributable
Other
485ms
0 KB
—
€8/mo
Costly
www.asu.edu
www.asu.edu
Other
436ms
148 KB
62%
€8/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
353ms
174 KB
37%
€6/mo
Costly
www.asu.edu
www.asu.edu
Other
323ms
15 KB
—
€6/mo
Costly
www.asu.edu
www.asu.edu
Other
318ms
523 KB
—
€6/mo
Costly
cassie.web.asu.edu
cassie.web.asu.edu
Other
275ms
7 KB
—
€5/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
247ms
168 KB
35%
€4/mo
Costly
Optimizely
cdn.optimizely.com
A/B Testing
234ms
89 KB
52%
€4/mo
Costly
Google Tag Manager
www.googletagmanager.com
Tag Manager
213ms
168 KB
36%
€4/mo
Costly
www.asu.edu
www.asu.edu
Other
163ms
37 KB
—
€3/mo
Optional
Google Tag Manager
www.googletagmanager.com
Tag Manager
157ms
129 KB
50%
€3/mo
Optional
www.asu.edu
www.asu.edu
Other
149ms
220 KB
43%
€3/mo
Optional
cscript-cdn-use.asu.edu
cscript-cdn-use.asu.edu
Other
84ms
165 KB
66%
€1/mo
Optional
Google Tag Manager
Tag Manager
Costly
Execution646ms
Transfer172 KB
Unused35%
Monthly Cost€11/mo
Unattributable
Other
Costly
Execution485ms
Transfer0 KB
Monthly Cost€8/mo
www.asu.edu
Other
Costly
Execution436ms
Transfer148 KB
Unused62%
Monthly Cost€8/mo
Google Tag Manager
Tag Manager
Costly
Execution353ms
Transfer174 KB
Unused37%
Monthly Cost€6/mo
www.asu.edu
Other
Costly
Execution323ms
Transfer15 KB
Monthly Cost€6/mo
www.asu.edu
Other
Costly
Execution318ms
Transfer523 KB
Monthly Cost€6/mo
cassie.web.asu.edu
Other
Costly
Execution275ms
Transfer7 KB
Monthly Cost€5/mo
Google Tag Manager
Tag Manager
Costly
Execution247ms
Transfer168 KB
Unused35%
Monthly Cost€4/mo
Optimizely
A/B Testing
Costly
Execution234ms
Transfer89 KB
Unused52%
Monthly Cost€4/mo
Google Tag Manager
Tag Manager
Costly
Execution213ms
Transfer168 KB
Unused36%
Monthly Cost€4/mo
www.asu.edu
Other
Optional
Execution163ms
Transfer37 KB
Monthly Cost€3/mo
Google Tag Manager
Tag Manager
Optional
Execution157ms
Transfer129 KB
Unused50%
Monthly Cost€3/mo
www.asu.edu
Other
Optional
Execution149ms
Transfer220 KB
Unused43%
Monthly Cost€3/mo
cscript-cdn-use.asu.edu
Other
Optional
Execution84ms
Transfer165 KB
Unused66%
Monthly Cost€1/mo
These scripts may cost more than they're worth
Google Tag Manager adds 646ms and costs ~€11/month
Unattributable adds 485ms and costs ~€8/month
www.asu.edu adds 436ms and costs ~€8/month
Google Tag Manager adds 353ms and costs ~€6/month
www.asu.edu adds 323ms and costs ~€6/month
www.asu.edu adds 318ms and costs ~€6/month
cassie.web.asu.edu adds 275ms and costs ~€5/month
Google Tag Manager adds 247ms and costs ~€4/month
Optimizely adds 234ms and costs ~€4/month
Google Tag Manager adds 213ms 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
Google Tag Manager takes 646ms 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 485ms 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.asu.edu takes 436ms 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
62% of www.asu.edu'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 353ms 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.asu.edu takes 323ms 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.asu.edu takes 318ms 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
cassie.web.asu.edu takes 275ms 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 247ms 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
Optimizely takes 234ms 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 Optimizely'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 213ms 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
50% of Google Tag Manager'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
66% of cscript-cdn-use.asu.edu'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.