B4J Question [ABMaterial] When or where we shouldn't use variables instead of hardcoded strings?

I can't remember when or where we should use hardcoded strings instead of variables, I think it had something to do with abmaterial analyzer. If someone can refresh my memory

I am asking because as my project gets bigger it kind of easy to type some string wrong and lose time finding what is wrong so I want to add all my controls ids and themes as constants strings - will I see a downside in performance doing this ?