Using inheritance - a table design question

Hi,

I am working on DB table design for an application. In the application, the account search is based on sex: male or
female. To have a better performance, I am thinking about to have two profile tables for each sex. Since the most of
data fields of the two tables are identical, for the design point of view, it is better to use the inheritance, that will have
three tables: person table and two its children tables: male and female. I am very new to Postgres and don't know any
its internal structure. Please enlighten me whether I shall use the inheritance for a large size of data or not.

Thanks,

Vernon