Laravel Eloquent Relationship Performance

I realize that in Laravel 4 Framework , when we have a relationship, instead of using JOIN of Mysql in the source code of Eloquent , it uses a select.

For example. I have these two Models.

class Usuario extends Eloquent{

   public function nivel()
   {
       return $this->belongsTo('Nivel');
   }
}

class Nivel extends Eloquent
{

}

When I make the following query:

$usuarios = Usuario::with('nivel')->get();

foreach($usuarios as $usuario) {

   echo $usuario->nivel->nome;
}

And I use DB::getQueryLog() , instead of displaying it:

SELECT * FROM usuarios JOIN niveis ON niveis.id = usuarios.nivel_id

It does this

SELECT * FROM usuarios
SELECT * FROM niveis WHERE id IN(5, 7, 8, 9, 10)

And that's because I used with('nivel') . For if I used to do this:

$usuarios = Usuario::all();

foreach($usuarios as $usuario){

   echo $usuario->nivel->nome;
}

The return of DB::getQueryLog() would be this, if there are 3 users:

SELECT * FROM usuarios
SELECT * FROM niveis WHERE id = 1
SELECT * FROM niveis WHERE id = 1
SELECT * FROM niveis WHERE id = 3

That is, when I do not specify with , if I have 100 users in the result, it will make 100 selects to relate to the table levels

I really like using Laravel 4 because of its great productivity and organization.

But I wonder if this "separate select" it does could lead to performance loss.