Golang TCP server - GC issue

Question

I have a TCP server which receives responds hex encoded messages. This works fine with lower traffic. It can handle 100, 200 messages per second. I face GC (garbage collection) issue at higher traffic and scripts stops responding and recovers after some time. Appreciate your valuable inputs on this.

var running bool = true

func main() {

    flag.IntVar(&lport, "lport", 5555, "Listen Port")
    flag.Parse()


    sockAddr :=  fmt.Sprintf(":%d", lport)
    TcpService(sockAddr)

}

func TcpService(addr string) {
    sockAddr, err := net.ResolveTCPAddr("tcp", addr)
    checkError(err)

    listener, err := net.ListenTCP("tcp", sockAddr)
    checkError(err)

    for running {
        conn, err := listener.Accept()
        if err != nil {
            continue
        }
        go serveConnection(conn, addr)
    }
}


func serveConnection(conn net.Conn, addr string) {
    defer conn.Close()

    var buf []byte
    data := make([]byte, 1024*1024)

    for running {
        n, err := conn.Read(data[0:])
        if err == io.EOF {
            //conn.Close()
            //return
        }
        if n > 0 {
            buf = append(buf, data[0:n]...)
            for {
                if len(buf) > 4 {
                    // Every message is of fixed length and length is encoded in buf[1:4]

                    msgLen  := decodeLength(buf[1:4])

                    if len(buf) >= msgLen {
                        go handleMsg(conn, buf[:msgLen])
                        buf = buf[msgLen:]

                    } else {
                        break
                    }

                } else {
                    break
                }
            }
        }
    }
}


func handleMsg(conn net.Conn, buf []byte) {
    /* validate the recieved message ie buf

    ....

    */

    var resp []byte
    ressp = append(resp, value1...)
    ressp = append(resp, value2...)
    ressp = append(resp, value3...)
    ressp = append(resp, value4...)

    //resp is a hex coded message ( hex bytes) of length varying from 1k to 5k bytes
    conn.Write(resp)

}