Smooth scrolling works with pad but not with keyboard

Hi community,

I got a strange issue and cant find the source for it.

i would like to scroll/move the camera with the keyboard (WASD). The following code works smooth, if i use a gamepad for moving the camera. If I use the keyboard (WASD) it's smooth for around 0,5 seconds, than it starts to stutter.

Here is the Code I use:

 void Update () {
         // Move camera via WASD/Pad
         float xAxisValue = Input.GetAxis("Horizontal");
         float zAxisValue = Input.GetAxis("Vertical");
         
         if (Camera.current != null)
         {
             transform.position += Vector3.left * xAxisValue * Time.deltaTime * moveSpeed;
             transform.position += Vector3.back * zAxisValue * Time.deltaTime * moveSpeed;
         }
     }

Hope you can help me out here.