Distance travelled by gameObject and behavior depend on device's performance?

I don't know if you're fully understanding why delta time is used. So here's a quick recap.

Say you have an object that you want to move at a constant speed, such as 100 units. To update its position, lets say you call a method UpdatePosition();

Assuming that UpdatePosition() is called within a physics engine loop, a separate thread, or a part of just some loop in general, that function is automatically at the mercy of the speed of that loop, or rather its rate is limited to how fast the things before it finish. That's fine and dandy.

This means that the speed of the object that you want to move will vary depending on how busy and how fast the CPU is.

One method of dealing with this, is instead of declaring an amount of space an object should move, you should instead figure out how much you want it to move per unit of time. So if we wanted to move the object 100 units every second, then a timer object should be used to record the time that it takes from the end of the last time you updated the object to the start of the following time you want to update the object. So if for some reason it took 3 seconds to get around to being able to update the object, and you have a rate of 100 units per second, then the value that the object will update by will be:

100 units * 3 seconds = 300 units

So some pseudocode would look like this:

void UpdatePosition()
{
    float timeOld = getOldTime();
    float timeCurrent = getSystemTime();
    float difference = timeCurrent - timeOld;

    float rate = 100.0f; // 100 units every second, on X Axis
    float desiredAmount = rate * difference;

    Vector3 desiredVector(desiredAmount, 0, 0);
    setOldTime(timeCurrent);
}

Now looking at the snippet of code you provided us:

variable1 -= variable2 * Time.deltaTime;
transform.position += new Vector3 (13, variable1 * Time.deltaTime, 0);

We can see that you have something similar, you have some sort of a rate defined as variable 2 multiplied by a change in time. You then proceed to take it away from some other var, variable1. That makes sense if you are treating variable 1 as like the momentum of the object or something, and are degrading it over time. However for some reason you are only doing this to the second value of the vector, or rather only its Y-Axis. Further, you're then multiplying it again by the rate. But none of this is done to that constant 13 you have for the X value