Stutter / Glitchy running character

Hi there, so I've spent few hours on this problem and I'm starting to be out of idea. If you have any idea, I'll be glad to hear it. FYI: This is my first game (but earning my life by doing c# )

Context: I'm doing a runner game base on some tutorial I saw on the net. I'm using the sample "Platformer2DUserControl" script to move my character permanently.

The problem: I'm getting some strange feeling about the background, not so smooth movement every seconds or so. The camera is attach to the character, so it took me some time to understand that the problem is coming from the character movement.

Here is a video (sorry took the first recording program I found) In order to see the problem I game the camera a regular move so that you can see the real movement of the caracter.

 void LateUpdate()
     {
         var x = transform.position.x + (Time.deltaTime * 14.5f);
         transform.position = new Vector3(x, 0, -10);
         //transform.position = new Vector3(player.position.x + 6, 0, -10);
     }

https://www.youtube.com/watch?v=Inb-Ja1nRLU&feature=youtu.be

At first I had a box collider but I read that it could some time have some unwanted colision. So in the purpose of testing I removed it and only use one circle colider

Not sure what's wrong, I'm doing some pretty basic stuff