Powershell Copy-Item Script schneller machen

$to_copy = get-content $liste
foreach($item in $to_copy) {
    copy-item -path "$quelle\$item" -destination "$ziel\$item" -Force -Recurse -verbose  
}

$quelle = 'D:\test\root'  
$ziel = 'D:\test\target'  
$liste = 'D:\liste.txt'  

function %% {
    [CmdletBinding()]
    param(
        [parameter(mandatory=$true,ValueFromPipeline=$true)][ValidateNotNullOrEmpty()][object[]]$InputObject,
        [parameter(mandatory=$true)][ValidateNotNullOrEmpty()][scriptblock]$Process,
        [parameter(mandatory=$false)][ValidateNotNullOrEmpty()][int]$ThrottleLimit = [System.Environment]::ProcessorCount,
        [parameter(mandatory=$false)][switch]$showprogress,
        [parameter(mandatory=$false)][ValidateNotNullOrEmpty()][hashtable]$params
    )
    begin{
        $rspool = [runspacefactory]::CreateRunspacePool(1,$ThrottleLimit)
        $rspool.ApartmentState = 'STA'  
        $rspool.Open()
        $jobs = New-Object System.Collections.ArrayList
        $objects = New-Object System.Collections.ArrayList
    }
    process{
        $InputObject | %{[void]$objects.Add($_)}
    }
    end{
        foreach ($obj in $objects){
            $ps = [Powershell]::Create()
            $ps.RunspacePool = $rspool
            [void]$ps.AddScript($Process).AddParameters(@{'_'=$obj;params=$params})  
            $job = $ps.BeginInvoke()
            [void]$jobs.Add(([pscustomobject]@{Handle = $job; Powershell = $ps}))
        }

        write-verbose "Waiting for all jobs to complete."  
        while(($jobs | ?{!$_.Handle.IsCompleted})){
            if ($showprogress.IsPresent){
                $completed = ($jobs | ?{$_.Handle.IsCompleted}).Count
                Write-Progress -Activity $PSCmdlet.MyInvocation.InvocationName -Status "Total of $($objects.Count) objects." -PercentComplete (($completed / $objects.Count) * 100) -CurrentOperation "Completed $completed of  $($objects.Count)."  
            }
        }
        # get results of jobs
        $results = $jobs | %{
            $_.Powershell.EndInvoke($_.handle)
            $_.Powershell.Dispose()
        }
        # cleanup
        $rspool.Close();$rspool.Dispose()
        $results
    }
}

gc $liste | ?{Test-Path "$quelle\$_"} | %% -ThrottleLimit 8 -showprogress -params @{quelle=$quelle;ziel=$ziel} -Process {  
    param($_,$params)
    copy-item -LiteralPath "$($params.Quelle)\$_" -Destination $params.ziel -Recurse -Force  
}