Is it worth to use reflection in this following case or is their a better solution?

I'm currently try to achieve a simplifed graphlql schema.
problem is: every domain model class takes 18 new classes in model and types to write a mutation set of add/delete and update.
My approche is to have 18 classes in total. Every class should be able to get any class of the domain model. I used generic classes and reflection to resolve to incoming classes.
But im uncertain, if it's really the best solution for this problem. Reflection will massivly slow down the app.