Player rapidly stutters back and forth while moving

I'm trying to create a 2.5d platformer and because of that my character's movement is restricted to the horizontal axis, the code I use lets him move and face the direction he's heading but whenever I move the thing keeps lagging backwards and forwards while moving.

     void Update () 
     {
 
         float moveHorizontal = Input.GetAxis("Horizontal");
 
         Vector3 newPosition = new Vector3(moveHorizontal, 0.0f, 0);
         transform.LookAt(newPosition + transform.position);
         transform.Translate(newPosition * speed * Time.deltaTime, Space.World);

Is what I'm using. The character is using a rigidbody, so I'm wondering if that might be the issue.

Regardless, how could I remedy this stuttering movement?