文件读取和编码性能

I'm writing some web service which supposed to receive an xml file from user, read it and save data to database

This file is gzipped and encoded in UTF-16. So i have to ungzip it, save xml to a file (for future purposes). Next i have to read file into a string, decode it to UTF-8 and kind of xml.Unmarshal([]byte(xmlString), &report)

Currently without saving it into a database

On my local machine i've realized that processing of one request takes about 30% of my CPU and about 300ms of time. For one request looks like okay. But i made script which simultaneously fires 100 requests (via curl ) and i saw that CPU usage is up to 100% and time for one request increased to 2sec

What i wanted to ask is: should i worry about it or maybe on a real web server things are going to be ok? Or maybe i'm doing smth wrong Here is the code:

func Parse(filename string) Report {
    xmlString := getXml(filename)
    report := Report{}

    xml.Unmarshal([]byte(xmlString), &report)

    return report
}



func getXml(filename string) string {
    b, err := ioutil.ReadFile(filename)
    if err != nil {
        fmt.Println("Error opening file:", err)
    }

    s, err := decodeUTF16(b)
    if err != nil {
        panic(err)
    }

    pattern := `<?xml version="1.0" encoding="UTF-16"?>`
    res := strings.Replace(s, pattern, "", 1)

    return res
}


func decodeUTF16(b []byte) (string, error) {
    if len(b)%2 != 0 {
        return "", fmt.Errorf("Must have even length byte slice")
    }

    u16s := make([]uint16, 1)

    ret := &bytes.Buffer{}

    b8buf := make([]byte, 4)

    lb := len(b)
    for i := 0; i < lb; i += 2 {
        u16s[0] = uint16(b[i]) + (uint16(b[i+1]) << 8)
        r := utf16.Decode(u16s)
        n := utf8.EncodeRune(b8buf, r[0])
        ret.Write(b8buf[:n])
    }

    return ret.String(), nil
}

Please ask if i forgot something important