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
53 images, 0 KB saveable
REVIEW
53 images, 0 KB saveable
Warning::
!
https://www.royalmail.com/sites/royalmail.com/file... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.royalmail.com/sites/royalmail.com/file... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.royalmail.com/sites/royalmail.com/file... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.royalmail.com/sites/royalmail.com/file... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://consent.trustarc.com/get?name=royal-mail-l... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.royalmail.com/sites/royalmail.com/file... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.royalmail.com/sites/royalmail.com/file... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
Warning::
!
https://www.royalmail.com/sites/royalmail.com/file... is missing width/height — may cause layout shift
Set explicit width and height to prevent CLS.
53images1.5 MB
0oversized-0 KB
50legacy format
8missing 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
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
14 fonts (299 KB)
PASS
14 fonts (299 KB)
Info::
i
14 font(s) use font-display: swap (FOUT risk but functional)
Web fonts
14
299 KB total
Render-blocking
0
of 14
Dominant font-display
swap
Most common across fonts
Font loading timeline
TransferFOIT (block)FOUT (swap)
RMFirstClass_W_In.woffwoffswap
Size16 KB
Load time252 ms
Start1.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
chevin-bold.woffwoffswap
Size35 KB
Load time309 ms
Start1.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
chevin-medium.woffwoffswap
Size34 KB
Load time95 ms
Start1.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
pfdintextstd-bold-webfo...woffswap
Size33 KB
Load time303 ms
Start1.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
RMFirstClass_W_Sd.woffwoffswap
Size12 KB
Load time36 ms
Start1.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
pfdintextstd-reg-webfon...woffswap
Size32 KB
Load time299 ms
Start1.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
PF_DIN_Regular.woffwoffswap
Size45 KB
Load time68 ms
Start2.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
chevin-bold.woffwoffswap
Size0 KB
Load time0 ms
Start2.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
chevin-medium.woffwoffswap
Size0 KB
Load time0 ms
Start2.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
pfdintextstd-bold-webfo...woffswap
Size0 KB
Load time0 ms
Start2.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
RMFirstClass_W_Sd.woffwoffswap
Size0 KB
Load time0 ms
Start2.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
pfdintextstd-reg-webfon...woffswap
Size0 KB
Load time0 ms
Start2.6 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
getotfswap
Size58 KB
Load time7 ms
Start2.9 s
RiskFOUT — text flashes from fallback to web font
Convert to woff2 for ~30% smaller file size
KFO7CnqEu92Fr1ME7kSn66a...woff2swap
Size34 KB
Load time35 ms
Start4.1 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 ~80 KB and ~160 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
Network Waterfall
129 requests over 7376ms
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-party2192ms · 407KB · £23/mo
Script
Category
Execution
Transfer
Unused
Monthly Cost
Verdict
www.royalmail.com
www.royalmail.com
Other
618ms
1 KB
22%
£6/mo
Costly
Unattributable
Unattributable
Other
498ms
0 KB
—
£5/mo
Costly
www.royalmail.com
www.royalmail.com
Other
326ms
64 KB
—
£3/mo
Costly
tags.tiqcdn.com
tags.tiqcdn.com
Other
211ms
126 KB
49%
£2/mo
Costly
s.go-mpulse.net
s.go-mpulse.net
Other
127ms
0 KB
66%
£1/mo
Optional
www.royalmail.com
www.royalmail.com
Other
119ms
1 KB
—
£1/mo
Optional
unpkg
unpkg.com
CDN
108ms
64 KB
60%
£1/mo
Optional
www.royalmail.com
www.royalmail.com
Other
73ms
36 KB
—
£1/mo
Optional
unpkg
unpkg.com
CDN
61ms
8 KB
—
£1/mo
Optional
www.royalmail.com
www.royalmail.com
Other
51ms
107 KB
80%
£1/mo
Optional
www.royalmail.com
Other
Costly
Execution618ms
Transfer1 KB
Unused22%
Monthly Cost£6/mo
Unattributable
Other
Costly
Execution498ms
Transfer0 KB
Monthly Cost£5/mo
www.royalmail.com
Other
Costly
Execution326ms
Transfer64 KB
Monthly Cost£3/mo
tags.tiqcdn.com
Other
Costly
Execution211ms
Transfer126 KB
Unused49%
Monthly Cost£2/mo
s.go-mpulse.net
Other
Optional
Execution127ms
Transfer0 KB
Unused66%
Monthly Cost£1/mo
www.royalmail.com
Other
Optional
Execution119ms
Transfer1 KB
Monthly Cost£1/mo
unpkg
CDN
Optional
Execution108ms
Transfer64 KB
Unused60%
Monthly Cost£1/mo
www.royalmail.com
Other
Optional
Execution73ms
Transfer36 KB
Monthly Cost£1/mo
unpkg
CDN
Optional
Execution61ms
Transfer8 KB
Monthly Cost£1/mo
www.royalmail.com
Other
Optional
Execution51ms
Transfer107 KB
Unused80%
Monthly Cost£1/mo
These scripts may cost more than they're worth
www.royalmail.com adds 618ms and costs ~£6/month
Unattributable adds 498ms and costs ~£5/month
www.royalmail.com adds 326ms and costs ~£3/month
tags.tiqcdn.com adds 211ms and costs ~£2/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.royalmail.com takes 618ms 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 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
www.royalmail.com takes 326ms 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
tags.tiqcdn.com takes 211ms 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 s.go-mpulse.net'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
60% of unpkg'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
80% of www.royalmail.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.