Unity Loopの速度比較

検証コード

LoopTest.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class LoopTest : MonoBehaviour 
{
    static readonly int TEST_COUNT = 10000;
    static readonly int ARRAY_NUM = 1000;
    int[] _LoopArray = new int[ARRAY_NUM];

    List<int> _LoopList = new List<int>();

    // Use this for initialization
    void Start () 
    {
        for (int i = 0; i < ARRAY_NUM; i++) {
            _LoopArray [i] = i;

            _LoopList.Add (i);
        }
    }

    // Update is called once per frame
    void Update () 
    {
        if(Input.GetKeyDown(KeyCode.A)) 
        {
            Test1 ();
        }

        if(Input.GetKeyDown(KeyCode.S)) 
        {
            Test2 ();
        }
    }

    void Test1()
    {
        var start = Time.realtimeSinceStartup;

        for (int test = 0; test < TEST_COUNT; test++) {
            for (int i = 0; i < ARRAY_NUM; i++) {
                var a = _LoopArray [i];
            }
        }

        var lap1 = Time.realtimeSinceStartup - start;

        start = Time.realtimeSinceStartup;

        for (int test = 0; test < TEST_COUNT; test++) {
            for (int i = 0; i < _LoopArray.Length; i++) {
                var a = _LoopArray [i];
            }
        }

        var lap2 = Time.realtimeSinceStartup - start;


        start = Time.realtimeSinceStartup;

        for (int test = 0; test < TEST_COUNT; test++) {
            foreach(var value in _LoopArray){
                var a = value;
            }
        }

        var lap3 = Time.realtimeSinceStartup - start;

        Debug.Log (lap1);    //0.08274078sec
        Debug.Log (lap2);    //0.06918979sec
        Debug.Log (lap3);    //0.07750511sec
    }

    void Test2()
    {
        var start = Time.realtimeSinceStartup;

        for (int test = 0; test < TEST_COUNT; test++) {
            for (int i = 0; i < ARRAY_NUM; i++) {
                var a = _LoopList [i];
            }
        }

        var lap1 = Time.realtimeSinceStartup - start;

        start = Time.realtimeSinceStartup;

        for (int test = 0; test < TEST_COUNT; test++) {
            for (int i = 0; i < _LoopList.Count; i++) {
                var a = _LoopList [i];
            }
        }

        var lap2 = Time.realtimeSinceStartup - start;


        start = Time.realtimeSinceStartup;

        for (int test = 0; test < TEST_COUNT; test++) {
            foreach(var value in _LoopList){
                var a = value;
            }
        }

        var lap3 = Time.realtimeSinceStartup - start;


        Debug.Log (lap1);    //0.1496518sec
        Debug.Log (lap2);    //0.2155538sec
        Debug.Log (lap3);    //0.3233421sec
    }
}

検証結果

	通常の配列	List
要素数で回す	0.08274078sec	0.1496518sec
length,countで回す	0.06918979sec	0.2155538sec
foreach	0.07750511sec	0.3233421sec

結論

要素数が固定なら配列を使ったほうが速い
配列は固定の変数よりlengthを使ったほうが速い