生成进程的执行时间在几周后会增加

当我使用System.Diagnostics.Process()创建进程时，我有一个奇怪的问题，即增加执行时间。我有一个"父"控制台应用程序，它周期性地(每隔几秒钟)创建其他"子"控制台应用程序。子进程完成一些工作(需要几百毫秒)然后退出。
一切正常运行大约4-12周。然后，子进程的执行时间开始缓慢增加。几周后，执行时间翻了一倍或三倍，越来越多的子进程被父应用程序杀死，父应用程序通过Process.WaitForExit(TimeOutValue)监视子进程的执行时间。现在我停止并重新启动"父"应用程序。之后，子进程的执行时间与开始时一样正常。
我监视了"父"应用程序的所有性能计数器。然而，没有增加的计数器。我无法理解"父"应用程序怎么会对"子"应用程序的执行时间产生如此大的影响。在下面的代码中，我剥离了不必要的部分，以专注于问题。有人知道这里出了什么问题吗?
OS为Windows Server 2008 R2 Standard

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Diagnostics;
using System.IO;
namespace Bss.CheckExecTimeScheduler
{
    class Program
    {
        static void Main(string[] args)
        {
            string Arg0 = "Bss.CheckTask.exe";
            string Args = "";
            int WaitForExit = 2000;
            int NumOfTimeOuts = 0;
            int NumOfNormalExits = 0;
            int NumOfExceptions = 0;
            long MinExecTime = 100000;
            long MaxExecTime = 0;
            Console.WriteLine("Press 'r' for a report ...");
            Console.WriteLine("Press 's' to start/stop execution ...");
            Console.WriteLine("Press 'q' to quit ...");
            Console.WriteLine("");
            while (true)
            {
                if (Console.KeyAvailable)
                {
                    ConsoleKeyInfo cki;
                    cki = Console.ReadKey();
                    if (cki.KeyChar == 'q')
                    {
                        return;
                    }
                    if (cki.KeyChar == 'r')
                    {
                        Console.WriteLine("");
                        Console.WriteLine("Normal Exits: " + NumOfNormalExits.ToString());
                        Console.WriteLine("Timeouts    : " + NumOfTimeOuts.ToString());
                        Console.WriteLine("Exceptions  : " + NumOfExceptions.ToString());
                        Console.WriteLine("Minimum execution time [ms]: " + MinExecTime.ToString());
                        Console.WriteLine("Maximum execution time [ms]: " + MaxExecTime.ToString());
                    }
                    if (cki.KeyChar == 's')
                    {
                        Console.WriteLine("Execution stopped. Press 's' to resume...");
                        while (true)
                        {
                            cki = Console.ReadKey();
                            if (cki.KeyChar == 's')
                            {
                                Console.WriteLine("Execution resumed...");
                                break;
                            }
                            else
                            {
                                Console.WriteLine("Illegal key. Execution stopped. Press 's' to resume...");
                            }
                        }
                    }
                }
                Stopwatch stopwatch = Stopwatch.StartNew();
                try
                {
                    System.Diagnostics.ProcessStartInfo procStartInfo = new System.Diagnostics.ProcessStartInfo(Arg0, Args);
                    procStartInfo.WindowStyle = ProcessWindowStyle.Hidden;
                    System.Diagnostics.Process proc = new System.Diagnostics.Process();
                    proc.StartInfo = procStartInfo;
                    proc.Start();
                    //AddMsg("Message: Command Thread launched. Arg0 = " + Arg0 + "; Args = " + Args + "; ProcessId = " + proc.Id.ToString());
                    if (proc.WaitForExit(WaitForExit) == false)
                    {
                        if (!proc.HasExited)
                        {
                            proc.Kill();
                            NumOfTimeOuts++;
                            AddExecTime("-1");
                        }
                        else
                        {
                            long elapsed = stopwatch.ElapsedMilliseconds;
                            NumOfNormalExits++;
                            if (elapsed < MinExecTime) MinExecTime = elapsed;
                            if (elapsed > MaxExecTime) MaxExecTime = elapsed;
                            AddExecTime(elapsed.ToString());
                        }
                    }
                    else
                    {
                        long elapsed = stopwatch.ElapsedMilliseconds;
                        NumOfNormalExits++;
                        if (elapsed < MinExecTime) MinExecTime = elapsed;
                        if (elapsed > MaxExecTime) MaxExecTime = elapsed;
                        AddExecTime(elapsed.ToString());
                    }
                }
                catch (Exception ex)
                {
                    NumOfExceptions++;
                    AddMsg("Exception catched: " + ex.Message);
                }
            }
        }
        public static void AddExecTime(string msg)
        {
            try
            {
                StreamWriter streamWriter = File.AppendText(DateTime.Now.ToString("yyyy.MM.dd") + "Bss.CheckExecTimeScheduler.ExecTimes.txt");
                streamWriter.WriteLine(msg);
                streamWriter.Close();
            }
            catch (Exception e)
            {
                Console.WriteLine("Error writing ExecTimes: Exception catched: " + e.ToString());
                Console.WriteLine(DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss.fff ") + msg);
            }
        }
        public static void AddMsg(string msg)
        {
            try
            {
                StreamWriter streamWriter = File.AppendText(DateTime.Now.ToString("yyyy.MM.dd") + "Bss.CheckExecTimeScheduler.Logfile.txt");
                streamWriter.WriteLine(DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss.fff ") + msg);
                streamWriter.Close();
            }
            catch (Exception e)
            {
                Console.WriteLine("Error writing logfile: Exception catched: " + e.ToString());
                Console.WriteLine(DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss.fff ") + msg);
            }
        }
    }   
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Diagnostics;
using System.IO;
namespace Bss.CheckTask
{
    class Program
    {
        static void Main(string[] args)
        {
            Stopwatch stopwatch = Stopwatch.StartNew();
            Console.WriteLine("Hello World");
            long elapsed = stopwatch.ElapsedMilliseconds;
            try
            {
                StreamWriter streamWriter = File.AppendText(DateTime.Now.ToString("yyyy.MM.dd") + "Bss.CheckTask.ExecTimes.txt");
                streamWriter.WriteLine(elapsed.ToString());
                streamWriter.Close();
            }
            catch (Exception e)
            {
                Console.WriteLine("Error writing Bss.CheckTask.ExecTimes.txt: Exception catched: " + e.ToString());
            }
        }
    }
}