Help With Database Import/Export

since i’m coming from a different Engine and i still have my excel to Datatable converter Tool created in C# i want to get able to reuse it in Unreal (but i’m wondering witch is the best way to get a big database to being imported in unreal ( performance wise)
what i mean i can convert it to a CSV file instead Datatable then serialize it and import the created binary files during the loading process of my games, but it will be quite slow… so there is any advice on it?