unity2d Box and Circle Colliders with Physics2DRaycast different behaviour?

I am having a square sprite and attached rigidbody2d and box collider to it and a simple character controller which checks grounded with physics2d.raycast function. When i play, the sprite moves, but after sometime it lags or to say it stops moving for few seconds and again it move. But instead of box collider i used circle collider that lag problem didnot appear. Why? Could someone explain. Also what is interpolate in rigidbody2d?
Here is the script by the way.

public class PlayerControll : MonoBehaviour
{

    public float MoveForce = 10;
    public float JumpForce = 6.3;
    public float MaxVelocity = 5;
    public LayerMask GroundLayer; //Ground is the layer mask
    public float GroundDistance = 0.4;

    void Update () 
    {	
	if(rigidbody2D.isKinematic) return;
	
	RaycastHit2D hit = Physics2D.Raycast(transform.position, new Vector2(0, -1), GroundDistance, GroundLayer);

	bool grounded = hit.collider != null;

	if (hit) 
	{        
		Debug.Log(hit.collider);
	}
	
	Debug.DrawRay(transform.position, new Vector2(0, -1), Color.red);
	
	if(Input.GetKeyDown(KeyCode.Space) && grounded)
	{
		rigidbody2D.AddForce(new Vector2(0, JumpForce), ForceMode2D.Impulse);
	}

	if(Input.GetKey(KeyCode.LeftArrow) && rigidbody2D.velocity.x > -MaxVelocity)
	{
		rigidbody2D.AddForce(new Vector2(-MoveForce, 0));
	}

	if(Input.GetKey(KeyCode.RightArrow) && rigidbody2D.velocity.x < MaxVelocity)
	{
		rigidbody2D.AddForce(new Vector2(MoveForce, 0));
	}
}
}

The issue you are experiencing with box colliders is explained in detail in the article Ghost Vertices. Read that carefully and you’ll understand the issue.

For what is Interpolate in Rigidbody2D, the manual page for Rigidbody2D states for Interpolate as:

Movement is smoothed based on the
object’s positions in previous frames.

So what it does is simply the position of the rigidbody in current frame is affected by its position in previous frame which yields a smooth result in rigidbody movement when it moves.