c#中string拼接的效率分析

using UnityEngine;
using UnityEngine.Profiling;
using System.Text;

#if UNITY_5_5_OR_NEWER
using TProfiler = UnityEngine.Profiling.Profiler;
#else
using TProfiler = UnityEngine.Profiler;
#endif

public namespace Test {

    /// string concat test
    public class TestString : MonoBehaviour {
        // Update is called once per frame
        void Update ()
        {
            // loop 10000times
            for(int i = 0; i < 10000; ++i) {

                TestString();
            }

            TestString10000();
        }

        // object new once
        private StringBuilder _sb = new StringBuilder();

        /// concat 10000 times
        private void TestString10000() {

            // +
            TProfiler.BeginSample("string.(10000+)");
            string s1 = string.Empty;
            for(int i = 0; i < 10000; ++i) {
                s1 = s1 + ((int)Time.time).ToString();
            }
            TProfiler.EndSample();


            // StringBuilder Append
            TProfiler.BeginSample("StringBuilder.10000Append");
            _sb.Clear();
            for(int i = 0; i < 10000; ++i) {
                _sb.Append((int)Time.time);
            }
            string s2 = _sb.ToString();
            TProfiler.EndSample();
        }

        /// concat 3 parts
        private void TestString() {

            System.Random random = new System.Random();

            // +
            TProfiler.BeginSample("string.(+)");
            string s1 = "txt_pre_" + random.Next().ToString() + "_end";
            TProfiler.EndSample();

            // Concat
            TProfiler.BeginSample("string.Concat");
            string s2 = string.Concat("txt_pre_", random.Next(), "_end");
            TProfiler.EndSample();

            // Concat ToString()
            TProfiler.BeginSample("string.Concat & int.ToString");
            string s3 = string.Concat("txt_pre_", ((int)Time.time).ToString(), "_end");
            TProfiler.EndSample();

            // format
            TProfiler.BeginSample("string.Format");
            string s4 = string.Format("txt_pre_{0}_end", (int)Time.time);
            TProfiler.EndSample();

            // format ToString()
            TProfiler.BeginSample("string.Format & int.ToString");
            string s5 = string.Format("txt_pre_{0}_end", ((int)Time.time).ToString());
            TProfiler.EndSample();

            // StringBuilder AppendFormat
            TProfiler.BeginSample("StringBuilder.AppendFormat & int.ToString");
            _sb.Clear();
            _sb.AppendFormat("txt_pre_{0}_end", ((int)Time.time).ToString());
            string s6 = _sb.ToString();
            TProfiler.EndSample();

            // StringBuilder Append
            TProfiler.BeginSample("StringBuilder.Append");
            _sb.Clear();
            _sb.Append("txt_pre_");
            _sb.Append((int)Time.time);
            _sb.Append("_end");
            string s7 = _sb.ToString();
            TProfiler.EndSample();

            // StringBuilder Append ToString()
            TProfiler.BeginSample("StringBuilder.Append & int.ToString");
            _sb.Clear();
            _sb.Append("txt_pre_");
            _sb.Append(((int)Time.time).ToString());
            _sb.Append("_end");
            string s8 = _sb.ToString();
            TProfiler.EndSample();

            // StringBuilder AppendNumber
            TProfiler.BeginSample("StringBuilder.AppendNumber");
            _sb.Clear();
            _sb.Append("txt_pre_");
            _sb.AppendNumber((int)Time.time);
            _sb.Append("_end");
            string s9 = _sb.ToString();
            TProfiler.EndSample();
        }
    }
}