IO中关于自定义缓冲区和使用默认缓冲区哪个效率更高的对比

//自己测试了一个3.8G的文件，有兴趣的可以自己试试看，初学java写的不对的地方希望大家能指出，有疑问可以留言一起探讨，谢谢！

package cn.String.Day.IO;

import java.io.*;

/**
 * Created by Void on 2017/6/20.
 */
        public class copyInputOutput {
            public static void main(String[] args) throws IOException {
                bufferTime();
                imbufferTime();

            }
    private static void imbufferTime() throws IOException {
        FileInputStream fileInputStream = new FileInputStream("D:\360安全浏览器下载\win7中文旗舰版64位系统.iso");
        FileOutputStream fileOutputStream = new FileOutputStream("e:\win7旗舰版64bit.iso");
        long startTime = System.currentTimeMillis() ;
        byte[] by = new byte[4096];
        int len = 0;
        while ((len = fileInputStream.read(by))!=-1){
            fileOutputStream.write(by,0,len);

        }
        fileOutputStream.close();
        fileInputStream.close();
        long endTime = System.currentTimeMillis();
        System.out.println("自定义缓冲花费的时间是："+(endTime-startTime)/1000);
    }

    private static void bufferTime() throws IOException {

        BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream("D:\360安全浏览器下载\win7中文旗舰版64位系统.iso"),4096);

        BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream("e:\win7旗舰版64bit.iso"),4096);
        long startTime = System.currentTimeMillis() ;
        int len = 0;
        while ((len = bufferedInputStream.read())!=-1){
            bufferedOutputStream.write(len);

        }
        bufferedOutputStream.close();
        bufferedInputStream.close();
        long endTime = System.currentTimeMillis();
        System.out.println("原缓冲花费的时间是："+(endTime-startTime)/1000);
    }
}