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
13 images, 0 KB saveable
REVIEW
13 images, 0 KB saveable
Warning::
!
https://m.media-amazon.com/images/G/01/digital/vid... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://m.media-amazon.com/images/G/01/digital/vid... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
13images98 KB
0oversized-0 KB
11legacy format
2missing 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
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
28 fonts (975 KB)
PASS
28 fonts (975 KB)
Info::
i
28 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
28
975 KB total
Render-blocking
0
of 28
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
51Ja06DDSWL.woffwoffswap
Size55 KB
Load time14 ms
Start839 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
51f91HNnSFL.woffwoffswap
Size53 KB
Load time13 ms
Start839 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
41j9-bPC0VL.woffwoffswap
Size28 KB
Load time19 ms
Start839 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
41dxSi+IUpL.woff2woff2swap
Size29 KB
Load time7 ms
Start917 ms
RiskFOUT — text flashes from fallback to web font
VjTR4RqBzY0mUYx.woff2woff2swap
Size22 KB
Load time7 ms
Start939 ms
RiskFOUT — text flashes from fallback to web font
pDxWAF1pBB0dzGB.woff2woff2swap
Size17 KB
Load time26 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
5167G3DwWTL.woff2woff2swap
Size38 KB
Load time46 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
AmazonEmber_Lt.woffwoffswap
Size53 KB
Load time36 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
KFPk-9IF4FqAqY-.woff2woff2swap
Size17 KB
Load time44 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
51J9qU3t-IL.woff2woff2swap
Size37 KB
Load time51 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
AmazonEmber_Rg.woffwoffswap
Size56 KB
Load time101 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
Dv1WQ5DdeMS5qP7.woff2woff2swap
Size28 KB
Load time117 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
WOnTLzkiaEccV7F.woff2woff2swap
Size18 KB
Load time107 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
2SazJx$EeTHfhMN.woff2woff2swap
Size18 KB
Load time103 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
ozb5-CLHQWI6Soc.woff2woff2swap
Size29 KB
Load time117 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
KwhNPG8Jz-Vz2X7.woff2woff2swap
Size23 KB
Load time112 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
lZemoC3awOEEzLR.woff2woff2swap
Size41 KB
Load time50 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
NvWNxKhmDbgI1lq.woff2woff2swap
Size42 KB
Load time119 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
1Ep1kWVX5g73xrY.woff2woff2swap
Size41 KB
Load time116 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
pnZF3$c0rgepEUt.woff2woff2swap
Size42 KB
Load time118 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
Wdqa3S7nfGc3Naj.woff2woff2swap
Size41 KB
Load time117 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
-w6hwcDxlefrOYI.woff2woff2swap
Size42 KB
Load time117 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
gyrV-mLs7VcgiFC.woff2woff2swap
Size34 KB
Load time113 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
8AuIu4whVB5EMoJ.woff2woff2swap
Size35 KB
Load time114 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
MexTn601PAhMvAn.woff2woff2swap
Size34 KB
Load time114 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
rlTCFdyUZFR9mQI.woff2woff2swap
Size34 KB
Load time114 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
ukoYNzKrqDRxhTq.woff2woff2swap
Size34 KB
Load time121 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
1yLvxs7jafx7AW$.woff2woff2swap
Size35 KB
Load time123 ms
Start1.3 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 ~74 KB and ~148 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
2
preload—
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
92 requests over 3938ms
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-party4375ms · 966KB · $25/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
www.primevideo.com
www.primevideo.com
Other
1224ms
123 KB
—
$7/mo
Costly
m.media-amazon.com
m.media-amazon.com
Other
731ms
105 KB
50%
$4/mo
Costly
Unattributable
Unattributable
Other
684ms
0 KB
—
$4/mo
Costly
m.media-amazon.com
m.media-amazon.com
Other
533ms
89 KB
87%
$3/mo
Costly
m.media-amazon.com
m.media-amazon.com
Other
266ms
81 KB
72%
$2/mo
Costly
m.media-amazon.com
m.media-amazon.com
Other
237ms
146 KB
59%
$1/mo
Costly
m.media-amazon.com
m.media-amazon.com
Other
191ms
32 KB
—
$1/mo
Optional
m.media-amazon.com
m.media-amazon.com
Other
173ms
84 KB
57%
$1/mo
Optional
m.media-amazon.com
m.media-amazon.com
Other
140ms
170 KB
66%
$1/mo
Optional
m.media-amazon.com
m.media-amazon.com
Other
91ms
60 KB
39%
$1/mo
Optional
m.media-amazon.com
m.media-amazon.com
Other
54ms
33 KB
—
$0/mo
Optional
m.media-amazon.com
m.media-amazon.com
Other
51ms
42 KB
—
$0/mo
Optional
www.primevideo.com
Other
Costly
Execution1224ms
Transfer123 KB
Monthly Cost$7/mo
m.media-amazon.com
Other
Costly
Execution731ms
Transfer105 KB
Unused50%
Monthly Cost$4/mo
Unattributable
Other
Costly
Execution684ms
Transfer0 KB
Monthly Cost$4/mo
m.media-amazon.com
Other
Costly
Execution533ms
Transfer89 KB
Unused87%
Monthly Cost$3/mo
m.media-amazon.com
Other
Costly
Execution266ms
Transfer81 KB
Unused72%
Monthly Cost$2/mo
m.media-amazon.com
Other
Costly
Execution237ms
Transfer146 KB
Unused59%
Monthly Cost$1/mo
m.media-amazon.com
Other
Optional
Execution191ms
Transfer32 KB
Monthly Cost$1/mo
m.media-amazon.com
Other
Optional
Execution173ms
Transfer84 KB
Unused57%
Monthly Cost$1/mo
m.media-amazon.com
Other
Optional
Execution140ms
Transfer170 KB
Unused66%
Monthly Cost$1/mo
m.media-amazon.com
Other
Optional
Execution91ms
Transfer60 KB
Unused39%
Monthly Cost$1/mo
m.media-amazon.com
Other
Optional
Execution54ms
Transfer33 KB
Monthly Cost$0/mo
m.media-amazon.com
Other
Optional
Execution51ms
Transfer42 KB
Monthly Cost$0/mo
These scripts may cost more than they're worth
www.primevideo.com adds 1224ms and costs ~$7/month
m.media-amazon.com adds 731ms and costs ~$4/month
Unattributable adds 684ms and costs ~$4/month
m.media-amazon.com adds 533ms and costs ~$3/month
m.media-amazon.com adds 266ms and costs ~$2/month
m.media-amazon.com adds 237ms and costs ~$1/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.primevideo.com takes 1224ms 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
m.media-amazon.com takes 731ms 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 m.media-amazon.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 684ms 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
m.media-amazon.com takes 533ms 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
87% of m.media-amazon.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
m.media-amazon.com takes 266ms 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
72% of m.media-amazon.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
m.media-amazon.com takes 237ms 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
59% of m.media-amazon.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 m.media-amazon.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
66% of m.media-amazon.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.