improve global task listing view performance

indigo_api/models/tasks.py

@@ -34,9 +34,9 @@ def get_queryset(self):
         from .documents import Document
 
         return super(TaskManager, self).get_queryset() \
-            .select_related('created_by_user', 'updated_by_user', 'assigned_to', \
-                            'submitted_by_user', 'reviewed_by_user', 'country', \
-                            'country__country', 'locality') \
+            .select_related('created_by_user', 'updated_by_user', 'assigned_to',
+                            'submitted_by_user', 'reviewed_by_user', 'country',
+                            'country__country', 'locality', 'locality__country', 'locality__country__country') \
             .prefetch_related(Prefetch('work', queryset=Work.objects.filter())) \
             .prefetch_related(Prefetch('document', queryset=Document.objects.no_xml())) \
             .prefetch_related('labels')

indigo_app/forms.py

@@ -366,7 +366,7 @@ class TaskFilterForm(forms.Form):
     assigned_to = forms.ModelMultipleChoiceField(queryset=User.objects)
     submitted_by = forms.ModelMultipleChoiceField(queryset=User.objects)
     type = forms.MultipleChoiceField(choices=Task.CODES)
-    country = forms.ModelMultipleChoiceField(queryset=Country.objects)
+    country = forms.ModelMultipleChoiceField(queryset=Country.objects.select_related('country'))
     taxonomy_topic = forms.CharField()
 
     def __init__(self, country, *args, **kwargs):

indigo_app/views/tasks.py

@@ -561,6 +561,7 @@ def get(self, request, *args, **kwargs):
     def get_queryset(self):
         tasks = Task.objects \
             .filter(assigned_to=None, country__in=self.request.user.editor.permitted_countries.all())\
+            .select_related('document__language', 'document__language__language') \
             .defer('document__document_xml')\
             .order_by('-updated_at')