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