Optimising references to other scripts

Questions & Answers
1

Hi there, I am making a game in which lots of different scripts on the same game object will reference each other frequently. So I am wondering what the best way to do this is for performance.

So first off, is referencing a variable from another script using:

variable = GetComponent<OtherScript> ().otherVariable;

any slower than referencing a variable from the same script, ie:

variable = otherVariable;

Secondly, though I guess the first question will answer this one… If I am using a variable from another script multiple times in each update/fixedupdate, would I be better off constantly referencing the variable from the other script, or would I be better off saving the variable as a variable within the same script first, and then referencing that? For example, which would be quicker:

this…

    void FixedUpdate () {

	LookForFood ();
	}

	void LookForFood () {

		if (GetComponent<AI> ().targetSearch == Vector3.zero || Vector3.Distance (transform.position, GetComponent<AI> ().targetSearch) < GetComponent<AI> ().searchDistance)
			
			NewSearchTarget ();
	}

	void NewSearchTarget () {
		
		GetComponent<AI> ().targetSearch.x = transform.position.x + Random.Range (-GetComponent<AI> ().searchRange, GetComponent<AI> ().searchRange);
		GetComponent<AI> ().targetSearch.y = transform.position.y + Random.Range (-GetComponent<AI> ().searchRange, GetComponent<AI> ().searchRange);
	}

or this…

    void FixedUpdate () {

	search = GetComponent<AI> ().targetSearch;
	distance = GetComponent<AI> ().searchDistance;
	range = GetComponent<AI> ().searchRange;

	LookForFood ();
	}

	void LookForFood () {

		if (search == Vector3.zero || Vector3.Distance (transform.position, search) < distance)
			
			NewSearchTarget ();
	}

	void NewSearchTarget () {
		
		search.x = transform.position.x + Random.Range (-range, range);
		search.y = transform.position.y + Random.Range (-range, range);
	}

I know the latter is easier to read, but in this case it wouldn’t matter too much because this script and similar ones are going to be about this short.

2

In general you don’t want to call GetComponent each frame because it has to search through the list of components on the target object. You should grab the component references you need once in Awake and save them to variables, then just use the variables.

So the latter of your two examples is better, but move the GetComponent calls out of FixedUpdate and into Awake.

edit: and by Start I of course meant Awake.