Parsing User Agents in GO (Golang) - Tobie/ua-parser

I am trying to stream (a lot) of user agents through a GO (Golang) program to extract different information about these ua agents like device type, OS, etc.

The GO code in Tobie Langel's UA Parser Repo looks very promising:

https://github.com/tobie/ua-parser/tree/master/go/uaparser

I created a simple program, in which I basically add streaming functionality to the example on the README page. To compare performance, I created the same type of simple program with a Ruby gem that uses a similar approach and same regexes.yaml file.

https://github.com/toolmantim/user_agent_parser

After compiling the Go program and testing both, the Ruby version is running 2-3 times faster than the GO version.

As far as I can see, both programs are loading and processing the ua agents in a similar manner.

I am new to GO and am wondering if anyone sees any major optimizations or fixes that could make programs using the GO portion of this repo run faster.

I am also interested to know if anyone knows of any other GO libraries I can use to parse user agents that work well.

---TESTING SIMPLE PROGRAMS TO COMPARE REGEX VS PCRE LIBS (as suggested in the comments below)

I have created the programs below, one using PCRE and one using the standard regex library. However, I don't seem to be getting a performance boost with PCRE. In fact, the PCRE library seems to be a little slower. Am I approaching this the wrong way?

--With standard regex library

package main

import (
  "fmt"
  "regexp"
  "strings"
  "bufio"
  "os"
)

func main() {

  var regex = regexp.MustCompile(`Mac`)
  scanner := bufio.NewScanner(os.Stdin)

  for scanner.Scan() {

    line := scanner.Text()
    fields := strings.Split(line, "\t")
    fmt.Println(regex.FindIndex([]byte(fields[0])))

  }

}  

--With PCRE library

package main

import (
  "fmt"
  pcre "github.com/glenn-brown/golang-pkg-pcre/src/pkg/pcre"
  "bufio"
  "os"
  "strings"
)

func main() {

  scanner:= bufio.NewScanner(os.Stdin)
  var regex = pcre.MustCompile(`Mac`, 0)

  for scanner.Scan() {

    line := scanner.Text()
    fields := strings.Split(line, "\t")
    fmt.Println(regex.FindIndex([]byte(fields[0]),0))

 }
}  

I would consider the rubex library. I changed ua-parser to use rubex instead, and I saw a 7x speed improvement. The library claims a 10x improvement, so I would give it a try with your particular application.