Should I use Vector3D in a 2D game?

I am currently following the 2D roguelike tutorial. Altough it is obviously a 2D game, in the scripts always a Vector3D is used. Are casts such expensive or what is the reason?

All Positions in Unity is vector 3. It doesn’t matter whether you use vector 2 or 3. Vector 2 simply set the z axis to zero. But your Camera should be in Orthographic mode.