a little Powershell Cmdle that makes performance measuring easier.

perfcounters.ps1

$script:perfstack = @()
$fullperfnames = $false


function measure-function([string] $__name, [scriptblock] $__command) {
    $__result = $null
    $__cmd = {
        $__result = Invoke-Command $__command
    }
    if ($script:perfstack -eq $null) {
        $script:perfstack = @() 
    }    
    $__isrecursion = $__name -in $script:perfstack
    $script:perfstack += "$__name"
    try {
        $__r = Measure-Command $__cmd
    
        if ($global:perfcounters -eq $null) {
            $global:perfcounters = @{}
        }
        if ($fullperfnames) {
            $__key = [string]::Join(">",$script:perfstack)
        } else {
            $__key = $__name
        }
        if ($global:perfcounters.ContainsKey($__key)) {
            if (!$__isrecursion) {
                $global:perfcounters[$__key].elapsed += $__r
            }
            $global:perfcounters[$__key].count++
        } else {
            $__props = [ordered]@{ name = "$__key"; elapsed = $__r; count = 1 } 
            $global:perfcounters[$__key] = new-object -type "pscustomobject" -property $__props  
        }
    
        if ($__result -ne $null) {
            return $__result
        }
    } finally {
        $script:perfstack = $script:perfstack | select -First ($script:perfstack.Length - 1)
    }
}

<#
# Usage:
# When you want to measure your functon "Get-Something"
  function Get-Something {
    # i'm doing some heavy loading here
    return $something
  }
# Add Measure-Function like this:
  function Get-Something {
    Measure-function  "$($MyInvocation.MyCommand.Name)" {
      # i'm doing some heavy loading here
      return $something
    }
  }

# then check results in $global:perfcounters hashtable
$global:perfcounters | format-table -AutoSize -Wrap | out-string | write-host
#>

I really liked your function and was using it to improve the performance of my scripts.
However, when using .NET HashSet objects, they are being converted to arrays when this wrapper is around the function.

I solved this by modifying the return like this (which works for all types of System.Collections.Generic.Hashset

            if ($__result.GetType().Name -like 'HashSet*') {
                # prevent expanding hashset causing it to become an array
                return ,$__result
            } else {
                return $__result
            }

Also, to check the results in powershell > 4.0 you simply do
$Global:perfcounters.Values | ft -Autosize