Lists or external TABLE?

Hi list,
i'm a postgres noob and before designing a new Database Schema i would
like to ask you a simple question because preformance will be a critical
point.

My question regards performance comparison between a Table which
includes a list or a Table without list and with an external table.

1 - TABLE A has several fields (most of which are types defined by me)
for a total of 30-40 field (counting fields in my new types) and could
contain 5000 rows.

2 - TABLE A will be accessed several times with several views or query.
(many SELECT,few UPDATE)

Let's suppose i need to add an info about addresses (which includes
country,city,cap....etc etc).
Addresses can vary from 1 to 20 entries..

Talking about performance is it better to include a list of addresses in
TABLE A or is it better to create an external TABLE B?

I'm afraid that including those addresses will decrease performance in
doing many SELECT.

On the other side i'm afraid of doing JOIN with TABLE B.

What do you think?
Thank you!

xchris