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
59 images, 0 KB saveable
REVIEW
59 images, 0 KB saveable
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a63... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/en-us/-/media/northamerica/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a91... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a61... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3ab0... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a1a... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a32... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/en-us/-/media/northamerica/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/Assets/RemoteOrder/img/shar... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a74... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3acb... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a7b... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3aba... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/en-us/-/media/northamerica/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/en-us/-/media/northamerica/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3ae9... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/en-us/-/media/project/remot... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3abc... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3ac9... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a5e... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a49... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/en-us/-/media/project/remot... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a4a... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/en-us/-/media/northamerica/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3a8e... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/en-us/-/media/northamerica/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://media.subway.com/dam/urn%3aaaid%3aaem%3aaf... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/en-us/-/media/northamerica/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/Assets/RemoteOrder/img/clos... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.subway.com/en-us/-/media/northamerica/... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
59images504 KB
0oversized-0 KB
47legacy format
30missing 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
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
11 fonts (750 KB)
PASS
11 fonts (750 KB)
Info::
i
11 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
11
750 KB total
Render-blocking
0
of 11
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
SubwaySans-Regular-Cy-G...woff2swap
Size49 KB
Load time31 ms
Start674 ms
RiskFOUT — text flashes from fallback to web font
SubwaySansLCG-Regular.woffwoffswap
Size113 KB
Load time61 ms
Start767 ms
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
SubwaySansCond-Medium.woffwoffswap
Size86 KB
Load time50 ms
Start940 ms
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
SubwaySansLCG-Bold.woffwoffswap
Size117 KB
Load time53 ms
Start940 ms
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
SubwaySansCond-Medium-W...woff2swap
Size36 KB
Load time54 ms
Start941 ms
RiskFOUT — text flashes from fallback to web font
KFO7CnqEu92Fr1ME7kSn66a...woff2swap
Size37 KB
Load time8 ms
Start1.1 s
RiskFOUT — text flashes from fallback to web font
SubwaySansLCG-Medium.woffwoffswap
Size117 KB
Load time21 ms
Start1.1 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
SubwaySans-Bold-Cy-Gr-W...woff2swap
Size54 KB
Load time51 ms
Start1.3 s
RiskFOUT — text flashes from fallback to web font
SubwaySans-Medium-Cy-Gr...woff2swap
Size54 KB
Load time40 ms
Start2.1 s
RiskFOUT — text flashes from fallback to web font
KFO7CnqEu92Fr1ME7kSn66a...woff2swap
Size0 KB
Load time0 ms
Start2.6 s
RiskFOUT — text flashes from fallback to web font
SubwaySansCond-Bold.woffwoffswap
Size87 KB
Load time29 ms
Start2.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
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 ~330 KB and ~660 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
186 requests over 6231ms
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-party11763ms · 1559KB · $156/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
www.subway.com
www.subway.com
Other
2310ms
24 KB
—
$31/mo
Costly
Unattributable
Unattributable
Other
1864ms
0 KB
—
$25/mo
Costly
www.subway.com
www.subway.com
Other
1437ms
341 KB
63%
$19/mo
Costly
cdn.quantummetric.com
cdn.quantummetric.com
Other
1272ms
101 KB
35%
$17/mo
Costly
www.subway.com
www.subway.com
Other
947ms
1 KB
21%
$13/mo
Costly
assets.adobedtm.com
assets.adobedtm.com
Other
859ms
262 KB
35%
$11/mo
Costly
www.subway.com
www.subway.com
Other
619ms
334 KB
60%
$8/mo
Costly
OneTrust
cdn.cookielaw.org
Consent
385ms
127 KB
53%
$5/mo
Essential
www.subway.com
www.subway.com
Other
338ms
41 KB
—
$4/mo
Costly
js-cdn.dynatrace.com
js-cdn.dynatrace.com
Other
304ms
79 KB
35%
$4/mo
Costly
app.link
app.link
Other
224ms
1 KB
—
$3/mo
Costly
www.subway.com
www.subway.com
Other
221ms
9 KB
—
$3/mo
Costly
assets.adobedtm.com
assets.adobedtm.com
Other
197ms
2 KB
—
$3/mo
Optional
www.subway.com
www.subway.com
Other
171ms
29 KB
—
$2/mo
Optional
sdk.apptentive.com
sdk.apptentive.com
Other
132ms
29 KB
—
$2/mo
Optional
ajax.googleapis.com
ajax.googleapis.com
Other
114ms
32 KB
66%
$2/mo
Optional
jsDelivr
cdn.jsdelivr.net
CDN
77ms
20 KB
—
$1/mo
Optional
OneTrust
cdn.cookielaw.org
Consent
67ms
9 KB
—
$1/mo
Essential
cdnjs
cdnjs.cloudflare.com
CDN
66ms
54 KB
88%
$1/mo
Optional
www.subway.com
www.subway.com
Other
55ms
5 KB
—
$1/mo
Optional
ajax.googleapis.com
ajax.googleapis.com
Other
55ms
31 KB
—
$1/mo
Optional
ajax.googleapis.com
ajax.googleapis.com
Other
50ms
30 KB
73%
$1/mo
Optional
www.subway.com
Other
Costly
Execution2310ms
Transfer24 KB
Monthly Cost$31/mo
Unattributable
Other
Costly
Execution1864ms
Transfer0 KB
Monthly Cost$25/mo
www.subway.com
Other
Costly
Execution1437ms
Transfer341 KB
Unused63%
Monthly Cost$19/mo
cdn.quantummetric.com
Other
Costly
Execution1272ms
Transfer101 KB
Unused35%
Monthly Cost$17/mo
www.subway.com
Other
Costly
Execution947ms
Transfer1 KB
Unused21%
Monthly Cost$13/mo
assets.adobedtm.com
Other
Costly
Execution859ms
Transfer262 KB
Unused35%
Monthly Cost$11/mo
www.subway.com
Other
Costly
Execution619ms
Transfer334 KB
Unused60%
Monthly Cost$8/mo
OneTrust
Consent
Essential
Execution385ms
Transfer127 KB
Unused53%
Monthly Cost$5/mo
www.subway.com
Other
Costly
Execution338ms
Transfer41 KB
Monthly Cost$4/mo
js-cdn.dynatrace.com
Other
Costly
Execution304ms
Transfer79 KB
Unused35%
Monthly Cost$4/mo
app.link
Other
Costly
Execution224ms
Transfer1 KB
Monthly Cost$3/mo
www.subway.com
Other
Costly
Execution221ms
Transfer9 KB
Monthly Cost$3/mo
assets.adobedtm.com
Other
Optional
Execution197ms
Transfer2 KB
Monthly Cost$3/mo
www.subway.com
Other
Optional
Execution171ms
Transfer29 KB
Monthly Cost$2/mo
sdk.apptentive.com
Other
Optional
Execution132ms
Transfer29 KB
Monthly Cost$2/mo
ajax.googleapis.com
Other
Optional
Execution114ms
Transfer32 KB
Unused66%
Monthly Cost$2/mo
jsDelivr
CDN
Optional
Execution77ms
Transfer20 KB
Monthly Cost$1/mo
OneTrust
Consent
Essential
Execution67ms
Transfer9 KB
Monthly Cost$1/mo
cdnjs
CDN
Optional
Execution66ms
Transfer54 KB
Unused88%
Monthly Cost$1/mo
www.subway.com
Other
Optional
Execution55ms
Transfer5 KB
Monthly Cost$1/mo
ajax.googleapis.com
Other
Optional
Execution55ms
Transfer31 KB
Monthly Cost$1/mo
ajax.googleapis.com
Other
Optional
Execution50ms
Transfer30 KB
Unused73%
Monthly Cost$1/mo
These scripts may cost more than they're worth
www.subway.com adds 2310ms and costs ~$31/month
Unattributable adds 1864ms and costs ~$25/month
www.subway.com adds 1437ms and costs ~$19/month
cdn.quantummetric.com adds 1272ms and costs ~$17/month
www.subway.com adds 947ms and costs ~$13/month
assets.adobedtm.com adds 859ms and costs ~$11/month
www.subway.com adds 619ms and costs ~$8/month
www.subway.com adds 338ms and costs ~$4/month
js-cdn.dynatrace.com adds 304ms and costs ~$4/month
app.link adds 224ms and costs ~$3/month
www.subway.com adds 221ms and costs ~$3/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.subway.com takes 2310ms 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 1864ms 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.subway.com takes 1437ms 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
63% of www.subway.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
cdn.quantummetric.com takes 1272ms 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.subway.com takes 947ms 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
assets.adobedtm.com takes 859ms 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.subway.com takes 619ms 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
60% of www.subway.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
53% of OneTrust'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
www.subway.com takes 338ms 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
js-cdn.dynatrace.com takes 304ms 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
app.link takes 224ms 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.subway.com takes 221ms 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
66% of ajax.googleapis.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
88% of cdnjs'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
73% of ajax.googleapis.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.
838 ms
1.7 s
2.5 s
3.4 s
4.2 s
5.0 s
5.9 s
6.7 s