multithread1.ps1

process {
    $SqlInstance = "MyServer";
    $SourceDb = "MySourceDb";
    $TargetDb = "MyTargetTb";
    $TableList = @("Table1","Table2","Table3","Table4");
    foreach ($Table in $TableList) {
        Start-ThreadJob -ThrottleLimit 4 -ArgumentList $SqlInstance, $SourceDb, $TargetDb, $Table -ScriptBlock {
            param($SqlInstance,
                $Source
                $Destination
                $TableName)
            Copy-DbaDbTableData -SqlInstance $SqlInstance -Database $Source -Destination $Destination -Table $TableName;
        }
    }
}