C#在文件读写结构体 Marshal效率低

using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Windows.Forms;

 using System.IO;
 using System.Runtime.InteropServices;

 namespace WindowsFormsApplication2
 {
 public partial class Form1 : Form
 {
 public Form1()
 {
 InitializeComponent();
 }

 private void button1_Click(object sender, EventArgs e)
 {
 string strFile = Application.StartupPath + "\\test.dat";
 if (!File.Exists(strFile))
 {
 MessageBox.Show("文件不存在");
 return;
 }

 FileStream fs = new FileStream(strFile, FileMode.Open,

 FileAccess.ReadWrite);
 TestStruct ts = new TestStruct();
 byte[] bytData = new byte[Marshal.SizeOf(ts)];
 fs.Read(bytData, 0, bytData.Length);
 fs.Close();
 ts = rawDeserialize(bytData);
 textBox1.Text = ts.dTest.ToString();
 textBox2.Text = ts.uTest.ToString();
 textBox3.Text = Encoding.Default.GetString(ts.bTest);
 }

 private void button2_Click(object sender, EventArgs e)
 {
 string strFile = Application.StartupPath + "\\test.dat";
 FileStream fs = new FileStream(strFile, FileMode.Create,
 FileAccess.Write);
 TestStruct ts = new TestStruct();
 ts.dTest = double.Parse(textBox1.Text);
 ts.uTest = UInt16.Parse(textBox2.Text);
 ts.bTest = Encoding.Default.GetBytes(textBox3.Text);
 byte[] bytData = rawSerialize(ts);
 fs.Write(bytData, 0, bytData.Length);
 fs.Close();
 }

 [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] //,Size=16
 public class TestStruct
 {
 [MarshalAs(UnmanagedType.R8)] //,FieldOffset(0)] 
 public double dTest;
 [MarshalAs(UnmanagedType.U2)] //, FieldOffset(8)]
 public UInt16 uTest;
 [MarshalAs(UnmanagedType.ByValArray, SizeConst = 6)]
 //, FieldOffset(10)]
 public byte[] bTest;
 }

 //序列化
 public static byte[] rawSerialize(object obj)
 {
 int rawsize = Marshal.SizeOf(obj);
 IntPtr buffer = Marshal.AllocHGlobal(rawsize);
 Marshal.StructureToPtr(obj, buffer, false);
 byte[] rawdatas = new byte[rawsize];
 Marshal.Copy(buffer, rawdatas, 0, rawsize);
 Marshal.FreeHGlobal(buffer);
 return rawdatas;
 }

 //反序列化
 public static TestStruct rawDeserialize(byte[] rawdatas)
 {
 Type anytype = typeof(TestStruct);
 int rawsize = Marshal.SizeOf(anytype);
 if (rawsize > rawdatas.Length)
 return new TestStruct();
 IntPtr buffer = Marshal.AllocHGlobal(rawsize);
 Marshal.Copy(rawdatas, 0, buffer, rawsize);
 object retobj = Marshal.PtrToStructure(buffer, anytype);
 Marshal.FreeHGlobal(buffer);
 return (TestStruct)retobj;
 }
 }
 }