Implement query optimization

ram/consist/admin.py

@@ -59,6 +59,13 @@ class ConsistAdmin(SortableAdminBase, admin.ModelAdmin):
     search_fields = ("identifier",) + list_filter
     save_as = True
 
+    def get_queryset(self, request):
+        """Optimize queryset with select_related and prefetch_related."""
+        qs = super().get_queryset(request)
+        return qs.select_related(
+            'company', 'scale'
+        ).prefetch_related('tags', 'consist_item')
+
     @admin.display(description="Country")
     def country_flag(self, obj):
         return format_html(

ram/consist/models.py

@@ -8,6 +8,7 @@ from django.core.exceptions import ValidationError
 
 from ram.models import BaseModel
 from ram.utils import DeduplicatedStorage
+from ram.managers import ConsistManager
 from metadata.models import Company, Scale, Tag
 from roster.models import RollingStock
 
@@ -35,6 +36,8 @@ class Consist(BaseModel):
         blank=True,
     )
 
+    objects = ConsistManager()
+
     def __str__(self):
         return "{0} {1}".format(self.company, self.identifier)