Design for Category Feature

Hi All,

I am building a contact management system and I have a
requirement for a contact category feature which allows a
contact record to belong to multiple categories. For example
a contact John Smith could belong to the categories
Architects, Friends and Suppliers. The user is presented
with a check list box and can check the categories that
apply to each contact. The user needs to be able to rename
the category names, or add categories of their own. This is
the structure I am using:

Table PERSON

PERSON_ID INTEGER PRIMARY KEY
FIRST_NAME VARCHAR
SURNAME VARCHAR
etc...

Table CATEGORY

CATEGORY_ID INTEGER PRIMARY KEY
PERSON_ID INTEGER PRIMARY KEY
CATEGORY_NAME_ID INTEGER PRIMARY KEY

Table CATEGORY_NAME

CATEGORY_NAME_ID INTEGER PRIMARY KEY
CATEGORY_NAME VARCHAR

My question is whether this is the optimal design for this
requirement? If I want to do a search for all contacts in
several categories, I need to do a join between all 3 tables
which sometimes impacts performance. The PERSON table may
have tens of thousands of records, and as a result the
CATEGORY table can have hundreds of thousands of records.
Your help is much appreciated. Thank you.

Regards,

DB

.