Huge magazine site. Multi DB ?

Hi guys !

I need an advice.

I am about to create a buddypress magazine site and transfert thousands of posts from joomla, and create a magazine style portal under buddypress.

There wont be much sub site (less than 10) but there will be about 15.000 up to 35.000 registered users.

Do that type of config require a multi DB ?

Thanks for clarification.