ServerManager serverManager = new ServerManager();
            ApplicationPoolCollection applicationPoolCollection = serverManager.ApplicationPools;


            Process process = Process.GetProcessById(applicationPoolCollection.Where(p => p.Name == "mywebsite.com").First().WorkerProcesses[0].ProcessId);

PerformanceCounter performanceCounter = new PerformanceCounter();

                performanceCounter.CategoryName = "Process";

                performanceCounter.CounterName = "Working Set";

                performanceCounter.InstanceName = process.ProcessName;
 Console.WriteLine(((uint)performanceCounter.NextValue() / 1024).ToString("N0"));