[Answered ]-Django model formset performance

You mentioned that there are ~500,000 rows in your database for the Attendance models. In Django, when the queryset parameter is not specified for a ModelFormSet, it includes all objects in that model. Django is probably fetching all 500,000 rows of data.

You need to figure out the queryset for your ModelFormSet. E.g.

def post(self, request, *args, **kwargs):
    queryset = Attendance.objects.none()
    formset = AcknowledgeFormset(queryset=queryset, data=request.POST)
    # continue with your regular code execution

The documentation contains a section for the queryset of a ModelFormSet: https://docs.djangoproject.com/en/1.9/topics/forms/modelforms/#django.forms.models.BaseModelFormSet