How to give smooth constant move to a player object

Hey everyone i am making a endless runner game. I use the code below for moving player constantly forward. Code works okey but sometimes player object having some shakes. It is keep going forward but looks like a move with lag(it is look like 1cm teleports to forward and back , but keep moving straight). So i need a smoother movement. I have tried some other movement pyhsics but they did not work well for me. So basically i need to move character at z axis constantly. Here is the code i use

public RigidBody rb;
forwardSpeed =5 ;
private void FixedUpdate()
        Vector3 forwardMove = transform.forward * forwardSpeed * Time.fixedDeltaTime;
        rb.MovePosition(rb.position + forwardMove);

From this I am assuming that you’re camera has the same script attached or same code to move with the player. If this is the case it might be that the code for the camera movement is in a Update or FixedUpdate function. If it is try changing it to LateUpdate which will mean every frame the player will render first which should stop the stuttering.
It would look something like this for the camera script:
private void LateUpdate(){
transform.Translate(Vector3.forward * speed * Time.deltaTime);