One million or more users may create problem with buddylist.

Hi,
I have a question about scalability issue of buddylist. Think I have a site with 1 million or more users and admin(or any user) have near about 200000 buddies or more. My question is can buddylist module handle the access of buddylist of admin specially when buddylist calls the function buddylist_get_buddies and execute a query :

$sql = 'SELECT b.buddy, u.name, u.mail, u.uid FROM {buddylist} b
INNER JOIN {users} u ON b.buddy = u.uid
WHERE b.uid = %d';
that's mean whenever this function call is made to fetch admin buddylist, a sql INNER JOIN will be made between 1000000 users and 200000 buddies of admin. So how buddylist can handle this situation?

Thanks