diff --git a/app/controllers/admin/customers_controller.rb b/app/controllers/admin/customers_controller.rb
index e0b44ec1d7..51ad5a519f 100644
--- a/app/controllers/admin/customers_controller.rb
+++ b/app/controllers/admin/customers_controller.rb
@@ -66,7 +66,12 @@ module Admin
       return Customer.where("1=0") unless json_request? && params[:enterprise_id].present?
 
       Customer.of(managed_enterprise_id).
-        includes(:bill_address, :ship_address, user: :credit_cards)
+        includes(:bill_address, :ship_address, user: :credit_cards).
+        joins(:orders).
+        merge(Spree::Order.complete.not_state(:canceled)).
+        group("customers.id").
+        select("customers.*").
+        select("SUM(total - payment_total) AS balance_value")
     end
 
     def managed_enterprise_id
diff --git a/app/serializers/api/admin/customer_serializer.rb b/app/serializers/api/admin/customer_serializer.rb
index cafc2a6a2f..1d8b2ffc3f 100644
--- a/app/serializers/api/admin/customer_serializer.rb
+++ b/app/serializers/api/admin/customer_serializer.rb
@@ -9,6 +9,8 @@ module Api
       has_one :ship_address, serializer: Api::AddressSerializer
       has_one :bill_address, serializer: Api::AddressSerializer
 
+      delegate :balance_value, to: :object
+
       def name
         object.name.presence || object.bill_address.andand.full_name
       end
@@ -51,11 +53,6 @@ module Api
 
         options[:customer_tags].andand[object.id] || []
       end
-
-      def balance_value
-        @balance_value ||=
-          OpenFoodNetwork::UserBalanceCalculator.new(object.email, object.enterprise).balance
-      end
     end
   end
 end
diff --git a/spec/features/admin/customers_spec.rb b/spec/features/admin/customers_spec.rb
index fe428fed00..4ff41be6c7 100644
--- a/spec/features/admin/customers_spec.rb
+++ b/spec/features/admin/customers_spec.rb
@@ -97,9 +97,9 @@ feature 'Customers' do
 
       describe "for a shop with multiple customers" do
         before do
-          mock_balance(customer1.email, managed_distributor1, 88)
-          mock_balance(customer2.email, managed_distributor1, -99)
-          mock_balance(customer4.email, managed_distributor1, 0)
+          build_balance(customer1, managed_distributor1, 88)
+          build_balance(customer2, managed_distributor1, -99)
+          build_balance(customer4, managed_distributor1, 0)
 
           customer4.update enterprise: managed_distributor1
         end
@@ -122,11 +122,12 @@ feature 'Customers' do
           end
         end
 
-        def mock_balance(email, enterprise, balance)
-          user_balance_calculator = instance_double(OpenFoodNetwork::UserBalanceCalculator)
-          expect(OpenFoodNetwork::UserBalanceCalculator).to receive(:new).
-            with(email, enterprise).and_return(user_balance_calculator)
-          expect(user_balance_calculator).to receive(:balance).and_return(balance)
+        def build_balance(customer, enterprise, balance)
+          order = build(:order, total: balance, payment_total: 0, distributor: enterprise)
+          order.email = customer.email
+          order.customer_id = customer.id
+          order.completed_at = Time.zone.now
+          order.save!
         end
       end