FindGameObjectsWithTag alternative for better perfomance

Questions & Answers
1

I've read that FindGameObjectsWithTag is quite a slow function. In my scene I call this function quite frequently the way seen in the code below.

Would it be a better practice to create a GameObject with a script component storing a static builtin array and adding every instance of the object at the time of instantiation and removing them when destroyed?

function FindTarget () : GameObject
{
    var allAtoms : GameObject [];
    allAtoms = GameObject.FindGameObjectsWithTag ("atom");

    var target : GameObject;
    var distance = Mathf.Infinity;
    var ownPosition = transform.position;

    for (var atom : GameObject in allAtoms)
    {
        var atomScript : Atom = atom.GetComponent (Atom) as Atom;
        if (charge == atomScript.charge * (-1) && atomScript.canMerge == true)
        {
            var difference = atom.transform.position - ownPosition;
            var currentDistance = difference.sqrMagnitude;
            if (currentDistance < distance)
            {
                target = atom;
                distance = currentDistance;
            }
        }
    }

    return target;
}
2

Are you experiencing performance problems? If not you can just leave it like it is. If you want to speed up things I would use a singleton manager with an atoms array or list (depending on what you need to do with them). Then all you have to do is add a line to the Start() of your atoms that registers itself with the manager and unregisters in OnDisable(). This way you will always have an up to date array/list of atoms and you don't need to recreate it every time.