It looks like this code is executing in parallel. There are many machines in the domain. I would like to finetune how many requests do in the same time for a sake of speed. How can set a throttle limit?
$comps = Get-ADComputer * -Properties description
$comps `
    | Select Name,
        @{name="User"; e={
            (Get-WMIObject -Class Win32_ComputerSystem -Computer $_.name).Username}},
        @{name="Description"; e={
            ($_.description)}} `
    | Out-GridView