hi
for starting a new a website i want to import a lot of account to the concrete Users table. these account include some extra information like tel, bank account, etc.
i think adding user attribute is not a good idea because:
1- import & sync these data would be a problem in the feature.
2- increasing number of users (about half million) cause slow queries.

first i want to know is it appropriate approach not using attribute in this situation?
and is there any guide for doing this?