Measure-CommandPerformance.ps1

##############################################################################
##
## Measure-CommandPerformance
##
## From Windows PowerShell Cookbook (O'Reilly)
## by Lee Holmes (http://www.leeholmes.com/guide)
##
##############################################################################

<#

.SYNOPSIS

Measures the average time of a command, accounting for natural variability by
automatically ignoring the top and bottom ten percent.

.EXAMPLE

PS > Measure-CommandPerformance.ps1 { Start-Sleep -m 300 }

Count    : 30
Average  : 312.10155
(...)

#>

param(
    ## The command to measure
    [Scriptblock] $Scriptblock,

    ## The number of times to measure the command's performance
    [int] $Iterations = 30
)

Set-StrictMode -Version 3

## Figure out how many extra iterations we need to account for the outliers
$buffer = [int] ($iterations * 0.1)
$totalIterations = $iterations + (2 * $buffer)

## Get the results
$results = 1..$totalIterations |
    Foreach-Object { Measure-Command $scriptblock }

## Sort the results, and skip the outliers
$middleResults = $results | Sort TotalMilliseconds |
    Select -Skip $buffer -First $iterations

## Show the average
$middleResults | Measure-Object -Average TotalMilliseconds