Why is this stuttering so much?

I'm attaching an extremely simple movement script. The game is a white cube moving across a black screen and repeats. No spawning, no sounds, no special effects and no gimmicks with the camera.

There is just one camera and one object in the scene.

I have looked around for answers to the stuttering question and people are sending basic answers like using TimeDelta / some other method. The script in this project contains both known methods for linear movement:

Update() with TimeDelta and RigigBody2D velocity. Easily switchable in code, same results.

Can somebody please point out what the solution might be? If not, I'd like this project to kick off a serious discussion of rampant stuttering - especially on Android.

Using this script on a simple 64x64 object, landscape mode deployment

 using UnityEngine;
 using System.Collections;
 
 public class Movement : MonoBehaviour {
 
     private Transform objTransform;
     private Vector3 pos;
     private Vector2 velocity = new Vector2(-6.0f, 0.0f);
 
     private int movementMethod = 0;
 
     // Use this for initialization
     void Start () {
         objTransform = gameObject.transform;
         pos = objTransform.localPosition;
     }
     
     // Update is called once per frame
     void Update () {
 
         if(movementMethod == 1)
         {
 
             pos.x -= Time.deltaTime * 6;
 
             if(pos.x < -7) {
                 pos.x = 7;
             }
 
             objTransform.localPosition = pos;
     
         }
 
     }
 
 
     void FixedUpdate() {
 
         if(movementMethod == 0)
         {
             this.rigidbody2D.velocity = velocity;
 
             if(objTransform.localPosition.x < -7.0f)
             {
                 objTransform.localPosition = new Vector3(7.0f, 0, 0);
             }
         }
     }
 }
 

Thank you for looking in to this. I believe this is really a major issue that is probably affecting so many people and I'm really surprised it isn't being discussed more.

I have fiddled around with target frame rate, vsync and any other settings that I could.