refactor: apply optimizations again

so the slowness went to the main query due to
tool's select_related not making MariaDB use the
index...

now with prefetch_related on both it seems pretty good

Author: arcstur

store/models.py

@@ -207,7 +207,8 @@ def tag_ids(self):
 
     @cached_property
     def sorted_tags(self):
-        return self.tags.order_by('-priority', 'id')
+        # tags come sorted through its Meta ordering
+        return self.tags.all()
 
     @cached_property
     def reverting_batches(self):

store/views.py

@@ -46,7 +46,11 @@ class APIBatchView(BatchView):
 
 class BatchesView(generics.ListAPIView):
     serializer_class = BatchSimpleSerializer
-    queryset = Batch.objects.all().order_by('-ended')
+    queryset = (
+        Batch.objects
+        .prefetch_related('tags', 'tool')
+        .order_by('-ended')
+    )
     template_name = 'store/batches.html'
     filter_fields = ('user',)
     filter_backends = (TaggingFilterBackend,)