Jittering render in simple 2D scene

Hi all. I try to make very simple 2D scene. I put background sprites from bot to top and move camera by script:

    void Update () {
         deltatime = Time.smoothDeltaTime;
         camerapos.y += speed*deltatime;  //float speed = 4.0f
         transform.position = camerapos;
     }

I also try to render at a specified frame rate Application.targetFrameRate = 60; to simulate most mobile device output. No rigidbodies/collider/ etc. attached just sprites. vSync - off. Every 3-4 sec all obj on scene is jittering. The effect is enhanced at 30fps limit. Does anyone know how to fix this? Thanks for the help.

Build for windows to see the problem