performance: prefetch categories for homepage (37->19)

panikweb/views.py

@@ -406,7 +406,7 @@ class Home(TemplateView):
                          'datetime': datetime(2007, 1, day+1)})
         context['days'] = days
 
-        context['episodes'] = Episode.objects.filter(
+        context['episodes'] = Episode.objects.prefetch_related('emission__categories').filter(
                 soundfile__podcastable=True, soundfile__fragment=False) \
                 .select_related().extra(select={
                     'first_diffusion': 'emissions_diffusion.datetime', },