为何FileStream复制文件效率比BufferedStream要高？

package day19;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
//BufferedOutputStream
//BufferedInputStream
public class CopyMp3 {
	public static void main(String[] args) {
		long start=System.currentTimeMillis();
		copy0();//非缓冲
		//copy1();//缓冲
		long end=System.currentTimeMillis();
		System.out.println(end-start);

	}
	public static void copy0(){

		FileOutputStream fos=null;
		FileInputStream fis=null;

		try{
			fos=new FileOutputStream("D:\Downloads\黑马_java基础\genymotion-2.2.0-vbox.exe");
			fis=new FileInputStream("D:\KuGou\genymotion-2.2.0-vbox.exe");
			byte[]buf=new byte[8192];
			int len=0;
			while((len=fis.read(buf))!=-1){
				fos.write(buf,0,len);
			}
		}catch(Exception e){
			throw new RuntimeException("cuowu");
		}finally{
			try {
				fis.close();
				fos.close();
			} catch (Exception e2) {
				// TODO: handle exception
			}

		}
	}
	public static void copy1(){
		BufferedInputStream bufi=null;
		BufferedOutputStream bufo=null;



		try{
			bufi=new BufferedInputStream(new FileInputStream("D:\KuGou\genymotion-2.2.0-vbox.exe"));
			bufo=new BufferedOutputStream(new FileOutputStream("D:\Downloads\黑马_java基础\genymotion-2.2.0-vbox.exe"));

			int by=0;
			while((by=bufi.read())!=-1){
				bufo.write(by);
			}
		}catch(Exception e){
			throw new RuntimeException("cuowu");
		}finally{
			try {
				bufi.close();
				bufo.close();
			} catch (Exception e2) {
				// TODO: handle exception
			}

		}

	}
}

代码运行后，copy0（）所用时间明显低于copy1（）所用时间，求解