private bool FileCopy(string source, string destination)
{
	int array_length = (int)Math.Pow(2, 19);
    byte[] dataArray = new byte[array_length];
    using (FileStream fsread = new FileStream(source, FileMode.Open, FileAccess.Read, FileShare.None, array_length))
	{
    	using (BinaryReader bwread = new BinaryReader(fsread))
        {
        	using (FileStream fswrite = new FileStream(destination, FileMode.Create, FileAccess.Write, FileShare.None, array_length))
			{	
				using (BinaryWriter bwwrite = new BinaryWriter(fswrite))
                {
                	for (;;)
                    {
                    	int read = bwread.Read(dataArray, 0, array_length);
                        
						if (0 == read) break;
						bwwrite.Write(dataArray, 0, read);
                     }
				}
			}
		}
	}

	//return string.Equals(CalcuateMD5(source), CalcuateMD5(destination)); //checksum 을 할 때만 사용. 안 할거면 그냥 void 로 선언
	return true;
}
 
private string CalcuateMD5(string fileName)
{
	using (var md5 = MD5.Create())
    {
    	using (var stream = File.OpenRead(fileName))
        {
        	var hash = md5.ComputeHash(stream);
            return BitConverter.ToString(hash).Replace("-", "").ToLowerInvariant();
		}
	}
}

private void button4_Click(object sender, EventArgs e)
        {
            DateTime start, end;
            double fileCopyDuration = 0, binaryWriteCopyDuration = 0;

            string sourceFilePath = @"..\Test\Source\Data.zip";
            string targetFolderPath = @"..\Test\Target\Data.zip";
            int maxCount = 10;
            bool binaryCopyResult = false;

            for (int count = 0; count < maxCount; ++count)
            {
                if (File.Exists(targetFolderPath)) File.Delete(targetFolderPath);

                start = DateTime.Now;
                File.Copy(sourceFilePath, targetFolderPath);
                end = DateTime.Now;

                fileCopyDuration += (end - start).TotalSeconds;

                if (File.Exists(targetFolderPath)) File.Delete(targetFolderPath);

                start = DateTime.Now;
                binaryCopyResult = FileCopy(sourceFilePath, targetFolderPath);
                end = DateTime.Now;

                binaryWriteCopyDuration += (end - start).TotalSeconds;
            }

            MessageBox.Show(string.Format("File Copy average duration: {0}sec, BinaryWriteCopy avg duration: {1}sec, BinaryWriteResult: {2}", 
                (fileCopyDuration / (double)maxCount), (binaryWriteCopyDuration / (double)maxCount), binaryCopyResult));
        }