находим 5 самых прожорливых процесса

[ssXXXss]

var query = (from p in System.Diagnostics.Process.GetProcesses()
             orderby p.PrivateMemorySize64 descending
             select p)
                 .Skip(0)
                 .Take(5)
                 .ToList();
return string.Join("\r\n", query);