$file  = '248966-Optimization-Reference-Manual-V1-049.pdf'   ; `
$range = 2..10                                               ; `
Write-Host "Query CIM for number of cores.."                 ; `
$query = Get-CimInstance -ClassName Win32_Processor          ; `
$corenum   = ($query |
            Measure-Object -Property NumberOfCores -Sum).Sum ; `
$threadnum = ($query |
         Measure-Object -Property NumberOfLogicalProcessors -Sum).Sum ; `
Write-Host "Physical cores : $corenum`r`nLogical cores  : $threadnum" ; `
$range | Foreach-Object -ThrottleLimit $corenum -Parallel {
    $core = "core $([System.Threading.Thread]::GetCurrentProcessorId())"
    $ps   = "page1&$("{0:d3}" -f $_).ps"
    $pdf  = "page1&$("{0:d3}" -f $_).pdf"
    Write-Host "[$core] $pdf  ...processing"
    & ".\gswin64c"            `
        -dQUIET               `
        -o $ps                `
        -sDEVICE=ps2write     `
        -sPageList="1,$_"     `
        $Using:file           `
        2> $null
        
    & ".\gswin64c"            `
        -dQUIET               `
        -o $pdf               `
        -sDEVICE=pdfwrite     `
        -dFastWebView         `
        $ps                   `
        2> $null
    Remove-Item $ps
    Write-Host "[$core] $pdf  ...done"
}