diff --git a/api/views.py b/api/views.py
index 15ada04..b1f8936 100644
--- a/api/views.py
+++ b/api/views.py
@@ -42,7 +42,6 @@ from .serializers import (
     AuthSerializer,
     CustomUserSerializer,
     CustomReadOnlyUserSerializer,
-    CustomReadOnlyUserByIDCardSerializer,
     UserProfileUpdateSerializer,
 )
 
@@ -579,16 +578,6 @@ def filter_temporary_user(request):
     )
 
 
-class ListUserByIDCardView(generics.ListAPIView):
-    # Create user API view
-    permission_classes = (permissions.AllowAny,)
-    serializer_class = CustomReadOnlyUserByIDCardSerializer
-    filter_backends = [DjangoFilterBackend]
-    filterset_fields = "__all__"
-    filterset_class = UserFilter
-    queryset = User.objects.all()
-
-
 class UserDetailAPIView(StaffEditorPermissionMixin, generics.RetrieveAPIView):
     queryset = User.objects.all()
     serializer_class = CustomReadOnlyUserSerializer
diff --git a/apibase/settings.py b/apibase/settings.py
index b91ac23..4ae2955 100644
--- a/apibase/settings.py
+++ b/apibase/settings.py
@@ -235,8 +235,11 @@ REST_FRAMEWORK = {
         "login": "1000/min",
     },
     "EXCEPTION_HANDLER": "api.exceptions.custom_exception_handler",
-    "DEFAULT_RENDERER_CLASSES": ("rest_framework.renderers.JSONRenderer",),
-    # "DEFAULT_SCHEMA_CLASS": "drf_spectacular.openapi.AutoSchema"
+    "DEFAULT_RENDERER_CLASSES": (
+        "rest_framework.renderers.JSONRenderer",
+        # "rest_framework.renderers.BrowsableAPIRenderer",
+    ),
+    # "DEFAULT_SCHEMA_CLASS": "drf_spectacular.openapi.AutoSchema",
 }
 
 
diff --git a/billing/views.py b/billing/views.py
index 77634d4..aad9276 100644
--- a/billing/views.py
+++ b/billing/views.py
@@ -13,6 +13,7 @@ from rest_framework.response import Response
 from api.mixins import StaffEditorPermissionMixin
 from api.tasks import add_new_devices_to_omada
 from apibase.env import BASE_DIR, env
+from django.db.models import Prefetch
 import logging
 
 from .models import Device, Payment, Topup, WalletTransaction
@@ -60,10 +61,18 @@ class ListCreatePaymentView(StaffEditorPermissionMixin, generics.ListCreateAPIVi
     filterset_class = PaymentFilter
 
     def get_queryset(self):
-        queryset = super().get_queryset()
-        if self.request.user.is_superuser:
-            return queryset
-        return queryset.filter(user=self.request.user)
+        unpaid_qs = Payment.objects.filter(paid=False).order_by("-created_at")
+        device_qs = Device.objects.prefetch_related(
+            Prefetch("payments", queryset=unpaid_qs, to_attr="unpaid_payments")
+        )
+        queryset = Payment.objects.select_related("user").prefetch_related(
+            Prefetch("devices", queryset=device_qs)
+        )
+
+        if not self.request.user.is_superuser:
+            queryset = queryset.filter(user=self.request.user)
+
+        return queryset
 
     def create(self, request):
         data = request.data
@@ -163,7 +172,7 @@ class UpdatePaymentAPIView(StaffEditorPermissionMixin, generics.UpdateAPIView):
 
 class VerifyPaymentView(StaffEditorPermissionMixin, generics.UpdateAPIView):
     serializer_class = PaymentSerializer
-    queryset = Payment.objects.all()
+    queryset = Payment.objects.select_related("user").all()
     lookup_field = "pk"
 
     def update(self, request, *args, **kwargs):
@@ -322,7 +331,7 @@ class VerifyPaymentView(StaffEditorPermissionMixin, generics.UpdateAPIView):
 
 
 class CancelPaymentView(StaffEditorPermissionMixin, generics.UpdateAPIView):
-    queryset = Payment.objects.all()
+    queryset = Payment.objects.select_related("user").all()
     serializer_class = PaymentSerializer
     lookup_field = "pk"
 
@@ -352,7 +361,7 @@ class CancelPaymentView(StaffEditorPermissionMixin, generics.UpdateAPIView):
 
 
 class ListCreateTopupView(StaffEditorPermissionMixin, generics.ListCreateAPIView):
-    queryset = Topup.objects.all()
+    queryset = Topup.objects.all().prefetch_related("user")
     serializer_class = TopupSerializer
     filter_backends = [DjangoFilterBackend]
     filterset_fields = "__all__"
diff --git a/devices/serializers.py b/devices/serializers.py
index a5dd133..f125f9c 100644
--- a/devices/serializers.py
+++ b/devices/serializers.py
@@ -36,9 +36,9 @@ class DeviceSerializer(serializers.ModelSerializer):
 
     def get_pending_payment_id(self, obj):
         unpaid_payment = (
-            Payment.objects.filter(devices=obj, paid=False)
-            .order_by("-created_at")
-            .first()
+            obj.unpaid_payments[0]
+            if hasattr(obj, "unpaid_payments") and obj.unpaid_payments
+            else None
         )
         return unpaid_payment.id if unpaid_payment else None
 
@@ -63,9 +63,9 @@ class AdminDeviceSerializer(serializers.ModelSerializer):
 
     def get_pending_payment_id(self, obj):
         unpaid_payment = (
-            Payment.objects.filter(devices=obj, paid=False)
-            .order_by("-created_at")
-            .first()
+            obj.unpaid_payments[0]
+            if hasattr(obj, "unpaid_payments") and obj.unpaid_payments
+            else None
         )
         return unpaid_payment.id if unpaid_payment else None
 
diff --git a/devices/views.py b/devices/views.py
index c5e3add..f27c03a 100644
--- a/devices/views.py
+++ b/devices/views.py
@@ -3,7 +3,9 @@ from xmlrpc.client import Boolean
 from rest_framework import generics, status
 from rest_framework.response import Response
 from django_filters.rest_framework import DjangoFilterBackend
+from billing.models import Payment
 from .models import Device
+from django.db.models import Prefetch
 from .serializers import (
     CreateDeviceSerializer,
     DeviceSerializer,
@@ -28,6 +30,13 @@ class DeviceListCreateAPIView(
     filterset_fields = "__all__"
     filterset_class = DeviceFilter
 
+    def get_queryset(self):
+        unpaid_qs = Payment.objects.filter(paid=False).order_by("-created_at")
+        base_qs = Device.objects.select_related("user").prefetch_related(
+            Prefetch("payments", queryset=unpaid_qs, to_attr="unpaid_payments")
+        )
+        return base_qs.all()
+
     def list(self, request, *args, **kwargs):
         queryset = self.filter_queryset(self.get_queryset())
         all_devices = request.query_params.get("all_devices", "false").lower() in [
@@ -90,7 +99,7 @@ class DeviceDetailAPIView(StaffEditorPermissionMixin, generics.RetrieveAPIView):
 
 
 class DeviceUpdateAPIView(StaffEditorPermissionMixin, generics.UpdateAPIView):
-    queryset = Device.objects.all()
+    queryset = Device.objects.select_related("user").all()
     serializer_class = CreateDeviceSerializer
     lookup_field = "pk"
 
@@ -116,7 +125,7 @@ class DeviceUpdateAPIView(StaffEditorPermissionMixin, generics.UpdateAPIView):
 
 
 class DeviceBlockAPIView(StaffEditorPermissionMixin, generics.UpdateAPIView):
-    queryset = Device.objects.all()
+    queryset = Device.objects.select_related("user").all()
     serializer_class = BlockDeviceSerializer
     lookup_field = "pk"
 
@@ -154,7 +163,7 @@ class DeviceBlockAPIView(StaffEditorPermissionMixin, generics.UpdateAPIView):
 
 
 class DeviceDestroyAPIView(StaffEditorPermissionMixin, generics.DestroyAPIView):
-    queryset = Device.objects.all()
+    queryset = Device.objects.select_related("user").all()
     serializer_class = DeviceSerializer
     lookup_field = "pk"