Profiler.BeginSample("string builder");
        stringBuilder.Remove(0, stringBuilder.Length);
        stringBuilder.AppendFormat("{0}{1}", a, b);
        string c1 = stringBuilder.ToString();
        Profiler.EndSample();

        Profiler.BeginSample("concat");
        string c2 = a + b;
        Profiler.EndSample();

        Debug.Log(c1 + " " + c2);