#Before: this will return each object after processing it
[vSphere PowerCLI] C:\> Get-VM | Get-VMUsefulStats | Measure-Object

Count    : 21
Average  :
Sum      :
Maximum  :
Minimum  :
Property :

[vSphere PowerCLI] C:\> Measure-Command{Get-VM | Get-VMUsefulStats}

Days              : 0
Hours             : 0
Minutes           : 0
Seconds           : 13
Milliseconds      : 637
Ticks             : 136377882
TotalDays         : 0.000157844770833333
TotalHours        : 0.0037882745
TotalMinutes      : 0.22729647
TotalSeconds      : 13.6377882
TotalMilliseconds : 13637.7882

#After: This will return array of objects after all have been proccessed
[vSphere PowerCLI] C:\> Get-VM | Get-VMUsefulStats | Measure-Object

Count    : 21
Average  :
Sum      :
Maximum  :
Minimum  :
Property :

[vSphere PowerCLI] C:\> Measure-Command{Get-VM | Get-VMUsefulStats}

Days              : 0
Hours             : 0
Minutes           : 0
Seconds           : 4
Milliseconds      : 712
Ticks             : 47129849
TotalDays         : 5.45484363425926E-05
TotalHours        : 0.00130916247222222
TotalMinutes      : 0.0785497483333333
TotalSeconds      : 4.7129849
TotalMilliseconds : 4712.9849