C++ :: Way / Pattern To Avoid Copying Data

I have a class buffer, which holds a std::string as member, and a socket_receive function:

struct buffer {
string data;
buffer() {}
buffer(buffer& b) : data(b.data) {}
};
buffer socket_receive() {
buffer tmp;
tmp.data = "1234";
return tmp;
}

so when I write

buffer b = socket_receive();

there is a copy constructor, and the tmp variable is constructed and destructed, is there anyway to improve the performance?

I tried the new c++11 move(), but seems even worse, I must be doing wrong with move(), but I don't know how.

#include <iostream>
#include <string>
#include <ctime>
using namespace std;
struct buffer {
string data;

[Code] .....