Because small group assignments can be created across classes, they cannot all be viewed on the Student Performance or a Class Performance page. However, there is a way to arrange small group assignments so that they do appear on a Class Performance page.
If you create class-wide assignments within a class and then exempt all the students not taking that assignment from the bottom of the assignment report (you get there, for assignments that students have not taken yet, from the assignment dashboard), then you can create de-facto individual or small group assignments that are only assigned to one or a few students. This will allow you to view all class data from a Student Performance > Class Performance page.
One other benefit of this method, aside from a centralized Student Performance and Class Performance page, is that you can later assign a student with that lesson by reassigning it to them from the exempted list; this helps keep your Assignments pages streamlined and easy to follow.