可以'；我找不到时间花在哪里

我有一个函数，它可以获取FTP文件夹中的文件列表。

功能：

    public static List<string> GetFileList(NetworkCredential credential, string FTPSite, string FTPFolder, string extension)
    {
        string LSOutput = "";
        List<string> files = new List<string>();
        bool isSuccess = false;
        int retrier = 1;
        while (isSuccess == false && retrier <= MaxRetries)
        {
            try
            {
                CommonHelper.PrepareLogAndEmail("--Attempt " + retrier + ":", LogMessageType.Simple);
                FtpWebRequest request = (FtpWebRequest)WebRequest.Create(@"ftp://" + FTPSite + FTPFolder);
                request.Timeout = 120000;
                request.Credentials = credential;
                request.UseBinary = true;
                request.EnableSsl = true;
                request.Method = WebRequestMethods.Ftp.ListDirectory;
                FtpWebResponse response = null;
                response = (FtpWebResponse)request.GetResponse();
                Stream responseStream = response.GetResponseStream();
                StreamReader reader = new StreamReader(responseStream);
                LSOutput = reader.ReadToEnd();
                reader.Close();
                response.Close();
                CommonHelper.PrepareLogAndEmail("--Succeeded", LogMessageType.Simple);
                isSuccess = true;
            }
            catch (Exception ex)
            {
                CommonHelper.PrepareLogAndEmail("--Failed. Details: " + ex.Message, LogMessageType.Error);
            }
            retrier++;
        }
        if (!isSuccess)
            throw new Exception("All attempts failed");
        else
        {
            //Parse the LS
            string[] LSOutputLines = LSOutput.Trim().Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
            foreach (string LSOutputLine in LSOutputLines)
                files.Add(LSOutputLine);
            //Filter files
            files = files.Where(f => f.ToLower().EndsWith(extension.ToLower())).ToList();
            PrepareLogAndEmail("Total " + extension.ToLower() + " files found: " + files.Count, LogMessageType.Simple);
            return files;
        }
    }

以下是它的名称：

        //-------------------------------------------------------//
        startTime = DateTime.Now;
        try
        {
            CommonHelper.PrepareLogAndEmail("Step 1: FIND FILES ON THE FTP FOLDER", CommonHelper.LogMessageType.StepStart);
            filesOnFolder = CommonHelper.GetFileList(credential, FTPSite, FTPFolder, ".pgp");
            if (filesOnFolder.Count == 0)
            {
                CommonHelper.PrepareLogAndEmail("Atleast one file was expected but not found", CommonHelper.LogMessageType.Simple);
                CommonHelper.PrepareLogAndEmail("Step 1: COMPLETED", CommonHelper.LogMessageType.StepComplete);
                CommonHelper.PrepareLogAndEmail("(Took " + (DateTime.Now - startTime).TotalSeconds + " seconds to complete)", CommonHelper.LogMessageType.TimeTaken);
                CommonHelper.PrepareLogAndEmail(HeaderMessage, CommonHelper.LogMessageType.Header);
                CommonHelper.SendMail(CommonHelper.EmailSubjectType.Informative);
                Environment.Exit(1);
            }
            else
            {
                CommonHelper.PrepareLogAndEmail("Step 1: COMPLETED", CommonHelper.LogMessageType.StepComplete);
                CommonHelper.PrepareLogAndEmail("(Took " + (DateTime.Now - startTime).TotalSeconds + " seconds to complete)", CommonHelper.LogMessageType.TimeTaken);
            }
        }
        catch (Exception ex)
        {
            CommonHelper.PrepareLogAndEmail("An exception occured. Details: " + ex.Message, CommonHelper.LogMessageType.Error);
            CommonHelper.PrepareLogAndEmail("Step 1: COMPLETED WITH ERRORS", CommonHelper.LogMessageType.StepComplete);
            CommonHelper.PrepareLogAndEmail("(Took " + (DateTime.Now - startTime).TotalSeconds + " seconds to complete)", CommonHelper.LogMessageType.TimeTaken);
            CommonHelper.PrepareLogAndEmail(HeaderMessage, CommonHelper.LogMessageType.Header);
            CommonHelper.SendMail(CommonHelper.EmailSubjectType.Bad);
            Environment.Exit(1);
        }
        //-------------------------------------------------------//

在某些情况下，我得到的输出为：

Step 1: FIND FILES ON THE FTP FOLDER
--Attempt 1:
--Succeeded
Total .pgp files found: 2
Step 1: COMPLETED
(Took 4.2742904 seconds to complete)

其中一个输出是这样的：

Step 1: FIND FILES ON THE FTP FOLDER
--Attempt 1:
--Failed. Details: The operation has timed out
--Attempt 2:
--Succeeded
Total .pgp files found: 0
Atleast one file was expected but not found
Step 1: COMPLETED
(Took 370.6597195 seconds to complete)

第一次尝试：120秒
第二次尝试（最坏情况）：119秒
总计：239秒

额外时间（370-239）：131秒

我不确定这131秒是在哪里度过的
PrepareLogAndEmail=将字符串记录到文本文件的函数
最大重试次数=3

Console.WriteLine("First retry (GetFileList)");
Console.ReadKey();
retrier++;

// Create new stopwatch
Stopwatch stopwatch = new Stopwatch();
// Begin timing
stopwatch.Start();
// Do something
// Stop timing
stopwatch.Stop();
// Result
var elapsedTime = stopwatch.Elapsed;