Middle Management Reporting in PowerShell

bad.ps1

$Properties = 'employeeID'

# Retrieve all workers with their "manager" attribute
Get-ADUser -Filter "title -like '*worker*'" -Properties @('manager';$Properties) |ForEach-Object {
  # Iterate over workers, retrieve each workers manager individually
  [pscustomobject]@{
    Worker = $_
    Manager = Get-ADUser -Identity $_.manager -Properties $Properties -ErrorAction SilentlyContinue
  }
}

better.ps1

$Properties = 'employeeID'

# Retrieve all workers with their "manager" attribute + desired filter attribute
$Users = Get-ADUser -Properties @('manager','title';$Properties) 

# Create a DN lookup table up front
$LookUpTable = $Users |ForEach-Object {$t = @{}} {
  $LookUpTable[$_.DistinguishedName] = $_
} {return $t}

$Users |Where-Object title -like *worker* |ForEach-Object {
  # Iterate over workers, fetch each workers manager from already populated lookup table
  [pscustomobject]@{
    Worker = $_
    Manager = $LookUpTable[$_.manager]
  }
}

cacheClass.ps1

using namespace System.Collections
using namespace Microsoft.ActiveDirectory.Management

class ADUserCache
{
    hidden [string[]]$Properties
    hidden [string]$KeyAttribute = 'DistinguishedName'
    hidden [IDictionary]$LookupTable 

    ADUserCache([string[]]$Properties){
        $this.LookupTable = @{}
        $this.Properties = $Properties
    }

    [ADUser]Get([string]$Key){
        if($this.LookupTable.Contains($Key)){
            return $this.LookupTable[$Key]
        }
        else{
            return ($this.LookupTable[$Key] = Get-ADUser -Identity $Key -Properties $this.Properties -SilentlyContinue)
        }
    }
}

$Properties = 'employeeID'
$cache = [ADUserCache]::new(@($Properties))

# Retrieve all workers with their "manager" attribute
Get-ADUser -Filter "title -like '*worker*'" -Properties @('manager';$Properties) |ForEach-Object {
  # Iterate over workers, retrieve each workers manager from cache instance (which will transparently fetch it if it doesn't exist)
  [pscustomobject]@{
    Worker = $_
    Manager = $cache.Get($_.manager)
  }
}

cached.ps1

$Properties = 'employeeID'

# Create an empty DN lookup table
$LookUpTable = @{}

# Retrieve all workers with their "manager" attribute
Get-ADUser -Filter "title -like '*worker*'" -Properties @('manager';$Properties) |ForEach-Object {
  # Iterate over workers, retrieve each workers manager from table if exists, otherwise query and cache 
  [pscustomobject]@{
    Worker = $_
    Manager = if($LookUpTable.ContainsKey($_.manager)){
        $LookUpTable[$_.manager]
      } 
      else{
        ($LookUpTable[$_.manager] = Get-ADUser -Identity $_.manager -Properties $Properties -ErrorAction SilentlyContinue)
      }
  }
}