From http://stackoverflow.com/questions/1760757/how-to-efficiently-concatenate-strings-in-go?answertab=active#tab-top

string.go

package main

import (
    "bytes"
    "fmt"
)

func main() {
    var buffer bytes.Buffer

    for i := 0; i < 1000; i++ {
        buffer.WriteString("a")
    }

    fmt.Println(buffer.String())
}