[Nodejs] Buffer vs String

Question

According to the official nodejs documentation, using Buffer for byte circulation is usually more efficient than converting to a String.
Is this all true?
This article uses a simple example of parsing the HTTP Request Header to solve this question.

HTTP Request Header Demo

POST /foo HTTP/1.1\r\nHost: foo.example.com\r\nContent-Length: 5\r\nConnection:keep-alive\r\nAccept:text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\nCookie:connect.sid=OY2nKGqI3obs5lYee0JKTjhf.FDtbY1Jz5Ngw5So9Jv3MUetI5ITvrIfwgCkRw%2FcXUCk\r\nUser-Agent:Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_2) AppleWebKit/535.7 (KHTML, like Gecko) Chrome/16.0.912.41 Safari/535.7\r\n\r\nq=bar

Requirement

Obtains the Host value in the Header.

Buffer version

var SPACE = 0x20, // ' '    COLON = 0x3a, // 58, :    NEWLINE = 0x0a, // \n    ENTER = 0x0d; // \rexports.parse = function parse(data) {    var line_start = 0, len = data.length;    for(var i = 0 ; i 

String version

exports.parse = function parse(data) {    var lines = data.toString('ascii').split("\n");    var cut, name, host;    for (var i = 0, len = lines.length; i 

Test script

var buffer_parse = require('./string-buffer-benchmark-parse-header-buffer').parse  , string_parse = require('./string-buffer-benchmark-parse-header-string').parse;var data = new Buffer('POST /foo HTTP/1.1\r\nHost: foo.example.com\r\nContent-Length: 5\r\nConnection:keep-alive\r\nAccept:text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\nCookie:connect.sid=OY2nKGqI3obs5lYee0JKTjhf.FDtbY1Jz5Ngw5So9Jv3MUetI5ITvrIfwgCkRw%2FcXUCk\r\nUser-Agent:Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_2) AppleWebKit/535.7 (KHTML, like Gecko) Chrome/16.0.912.41 Safari/535.7\r\n\r\nq=bar');//console.log(buffer_parse(data));//console.log(string_parse(data), data.length);var n = 1000000;var start = new Date();for(var i = 0; i 

Test Results

$ node string-buffer-benchmark.jsbuffer_parse take: 1888 msstring_parse take: 4948 ms

Conclusion

Buffer is much faster than String.