Why does this simple follow script make my game lag?

Questions & Answers
1

It makes my game lag when I apply it to an object. All it’s supposed to do is follow my character without modifying the y position so it always stays on the ground. If it collides with my character then my character loses 1 hitpoint. Here’s a screen shot of the settings for the rigidbody and other components of the enemy that I applied this script to. http://i.imgur.com/yDpFhAG.png?1 The little crab like things are what the enemy looks like.

It looks like it I remove transform.LookAt(Player.transform.position); it stops lagging. Does anyone know why?

NEW FINDING Changing collision detection to discrete also makes the problem go away, even in the presence of transform.LookAt.

public float Speed;

    void Start () {
       Player = GameObject.FindWithTag("Player");
       transform.LookAt(Player.transform.position);
    }
 
    void FixedUpdate()
    {
         SeekTarget();
    }

    void SeekTarget()

    {
       Vector3 MoveTowardsPosition = Vector3.MoveTowards(transform.position,Player.transform.position, Speed * Time.deltaTime);
       MoveTowardsPosition.y = transform.position.y;
       rigidbody.MovePosition(MoveTowardsPosition);

       transform.LookAt(Player.transform.position);
    }
3

Changing the collision detection from continuous dynamic to discrete worked. Alternatively not rotating the object also made the problem go away. Explanation by @Dracorat as to the why of the problem:

“Continuous dynamic attempts to alter a RigidBody’s position if it’s intersecting with another. Since the usual alter direction would be invalid, it is struggling with it. It’s also a very expensive algorithm. You’d use it only if you believe an object is moving so fast that it might pass completely through something in between frames.”

2

Hmmm, not sure why it lags. I played around with a simple ‘follow-player’ script. It never turned out into anything useable but I simply med use of the Vector3.Lerp command. Check into that, maybe it can help you out. Best of luck!