Why my oncomplete method is called after 1-2 second in itween.moveto() function

Question

Here is the code portion.

public void Move(Transform SelectedTarget)
{
        target.transform.LookAt(base.transform.position);
        base.transform.LookAt(SelectedTarget.transform.position);
        anim.SetTrigger("Move");

        //base.transform.position = Vector3.MoveTowards(base.transform.position,             SelectedTarget.transform.position , Time.deltaTime * 4);
        //base.transform.position = SelectedTarget.transform.position;
        iTween.MoveTo(base.gameObject, iTween.Hash("position", SelectedTarget.position,"speed",7f,"oncomplete","MoveComplete"));
    
        Debug.Log("Move Called");  
    }


 public void KilledBy(Enemy enemyObject)
    {
        killedByLookPos = enemyObject.transform.position;
    }

    public void MoveComplete()
    {
        Debug.Log("attack");
        anim.SetTrigger("Attack");
        manager.EnemyTurn();
        target.EnemyKilled();
    
    }

I want to call the movecomplete method quickly as soon as player completes the movement but it is delayed by 1-2 seconds