I've created some helper functions in a custom base class all my game objects will derive from, will this be slow?

Questions & Answers
1

It’s mostly to reduce the amount of code I have to write:

public class MyObject : MonoBehaviour {
	
	public static bool IsComputerBuild
	{
		get
		{
#if UNITY_STANDALONE_OSX||UNITY_STANDALONE_PC||UNITY_WEBPLAYER||UNITY_EDITOR
			return true;		
#else
			return false;
#endif
		}
	}


    public virtual Vector3 LocalScale
    {
        get
        {
            return transform.localScale;
        }
        set
        {
            transform.localScale = value;
        }
    }

    public virtual Vector3 Position
    {
        get
        {
            return transform.position;
        }
        set
        {
            transform.position = Position;
        }
    }
	
	public virtual float PosX
	{
		set
		{
			Vector3 pos = transform.position;
			pos.x = value;
			transform.position = pos;
		}
		get
		{
			return transform.position.x;
		}
	}
	
	public virtual float PosY
	{
		set
		{
			Vector3 pos = transform.position;
			pos.y = value;
			transform.position = pos;
		}
		get
		{
			return transform.position.y;
		}
	}
	
	public virtual float PosZ
	{
		set
		{
			Vector3 pos = transform.position;
			pos.z = value;
			transform.position = pos;
		}
		get
		{
			return transform.position.z;
		}
	}
	
	public virtual float RotZ
	{
		set
		{
			value = MyMath.Normalize(value, 0, 2 * Mathf.PI);
			transform.rotation = Quaternion.AngleAxis(value * Mathf.Rad2Deg, new Vector3(0,0,1));
		}
		get
		{
			float rot;
			Vector3 dir = new Vector3(0,0,1);
			transform.rotation.ToAngleAxis(out rot, out dir);
			return MyMath.Normalize(rot * Mathf.Deg2Rad, 0, 2*Mathf.PI);
		}
	}
	
	public virtual float ScaleY
	{
		get
		{
			return transform.localScale.y;
		}
		set
		{
			Vector3 scale = transform.localScale;
			scale.y = value;
			transform.localScale = scale;
		}
	}
	
	public virtual float ScaleX
	{
		get
		{
			return transform.localScale.x;
		}
		set
		{
			Vector3 scale = transform.localScale;
			scale.x = value;
			transform.localScale = scale;
		}
	}
	
	// Use this for initialization
	void Start () {
	
	}
	
	// Update is called once per frame
	void Update () {
	
	}
	
	public static float PI
	{
		get
		{
			return Mathf.PI;
		}
	}
}
3

When in doubt, profile some heavy use cases. Because everything I’m posting here are unsubstantiated educated guesses.

Technically: yes, you’re making the game slower - by adding an additional layer between the MonoBehavior class and your objects you add an additional traversal step through the vtable every time a virtual function for a gameObject is called. But whether you will ever notice that slowness is questionable.
The built-in Unity classes already make heavy use of inheritance, for example: Object->Component->Behavior->MonoBehavior. It’s debatable whether one additional layer will change the performance characteristics - especially considering that with Unity, you’ve already committed to an environment that trades off the micro-level performance that could be gained with a statically compiled language for the convenience and dynamic nature of JIT and bytecode (which is slower by definition). And Unity seems to be doing just fine when it comes to performance for many, many games.

My feeling is that you’re more likely to inadvertently impact performance by doing an unnoticed unnecessary square root calculation in one of your Update() functions than by one additional layer of indirection, and that you shouldn’t worry about your extra class inheritance.

2

Most likely this wont affect performance. Everything inherits from object class anyways. This might affect performance a tint bit, but that wont be noticeable.

Edit: typed on smartphone