Avoid N+1 when loading tax rates index

Author: chaimann

admin/app/controllers/solidus_admin/tax_rates_controller.rb

@@ -6,6 +6,10 @@ class TaxRatesController < SolidusAdmin::ResourcesController
 
     def resource_class = Spree::TaxRate
 
+    def resources_collection
+      resource_class.includes(:zone, :tax_categories, :calculator)
+    end
+
     def resources_sorting_options = { created_at: :desc, id: :desc }
 
     def permitted_resource_params