How to serialize data more efficiently in Django Rest Framework?

The part of my problem is solved by the question: #72534250
I understood that the path I was following was wrong, and I should change the optimization of the models to serializers and/or viewsets.
But how?

I had this structure:
*I already removed element_name and element_text from Models Foo

    class User(models.Model):
        name = models.CharField(max_lenth=50)
        age = models.IntergerField()

    class Customer(models.Model):
        user = models.ForeingKey(User, on_delete=models.CASCADE, verbose_name='User')

    class Element(models.Model):
        name = models.CharField(max_lenth=50)
        text = models.TextField()
        

    class Bar(models.Model):
        element = models.ForeingKey(Element, on_delete=models.CASCADE, verbose_name='Element')

    class Foo(models.Model):
        bar = models.OneToOneField(Bar, on_delete=models.CASCADE, verbose_name='Bar')
        customer = models.ForeingField(Customer, on_delete=models.CASCADE, verbose_name='Customer')
        is_active = models.BooleanField('Is Active', default=False)
        
        def user(self):
            return self.customer.user
        
        # Removed
        def element_name(self):
            return self.bar.element.name

        # Removed
        def element_text(self):
            return self.bar.element.text

And these serializers:

    class UserSerializer(ModelSerializer):
        class Meta:
            model = User
            fields = '__all__'

    class CustomerSerializer(ModelSerializer):
        class Meta:
            model = Customer
            fields = '__all__'

    class ElementSerializer(ModelSerializer):
        class Meta:
            model = Element
            fields = '__all__'

    class BarSerializer(ModelSerializer):
        element = ElementSerializer()

        class Meta:
            model = Bar
            fields = '__all__'

    class FooSerializer(ModelSerializer):
        bar = BarSerializer()
        user = UserSerializer()
        
        class Meta:
            model = Foo
            fields = '__all__'

And this viewset:

    class FooViewSet(ModelViewSet):
        serializer_class = FooSerializer
        permission_classes = [IsAuthenticated]
        authentication_classes = [JWTAuthentication]
        http_method_names = ['get', 'post', 'patch']

        def get_queryset(self):
           active = self.request.query_params.get('is_active', False)
           name = self.request.query_params.get('name', '')
           data = {'is_active': active}
           if name == 'Fire':
              data['bar__element__name'] = name
           queryset = Foo.objects.filter(**data)
           return queryset
        

I try this tutorial, but I didn't notice any real performance improvement. So I'm looking for another way to solve this problem.

I thought... If I just put select_related(...) in the return of get_queryset, how Django Rest would identify that it is to serialize the cached data? Would that really improve performance?

I also need element_name, element_text and object user to be returned in the GET of FooViewSet. How can I return them in the most efficient way?