diff --git a/core/auth/mixins.py b/core/auth/mixins.py
index b8d8ee10..28012d50 100644
--- a/core/auth/mixins.py
+++ b/core/auth/mixins.py
@@ -307,6 +307,7 @@ class PermissionOrClubBoardRequiredMixin(PermissionRequiredMixin):
             return False
         if super().has_permission():
             return True
-        return self.club is not None and any(
-            g.id == self.club.board_group_id for g in self.request.user.all_groups
+        return (
+            self.club is not None
+            and self.club.board_group_id in self.request.user.all_groups
         )
diff --git a/core/models.py b/core/models.py
index a5ae84a3..3b533751 100644
--- a/core/models.py
+++ b/core/models.py
@@ -356,10 +356,10 @@ class User(AbstractUser):
         )
         if group_id is None:
             return False
-        return any(g.id == group_id for g in self.all_groups)
+        return group_id in self.all_groups
 
     @cached_property
-    def all_groups(self) -> list[Group]:
+    def all_groups(self) -> dict[int, Group]:
         """Get the list of groups this user is in."""
         additional_groups = []
         if self.is_subscribed:
@@ -372,14 +372,11 @@ class User(AbstractUser):
             # a UNION rather than a OR (in average, 0.25ms vs 14ms).
             # For the why, cf. https://dba.stackexchange.com/questions/293836/why-is-an-or-statement-slower-than-union
             qs = qs.union(Group.objects.filter(id__in=additional_groups))
-        return list(qs)
+        return {g.id: g for g in qs}
 
     @cached_property
     def is_root(self) -> bool:
-        if self.is_superuser:
-            return True
-        root_id = settings.SITH_GROUP_ROOT_ID
-        return any(g.id == root_id for g in self.all_groups)
+        return self.is_superuser or settings.SITH_GROUP_ROOT_ID in self.all_groups
 
     @cached_property
     def is_board_member(self) -> bool:
@@ -1106,8 +1103,7 @@ class PageQuerySet(models.QuerySet):
             return self.filter(view_groups=settings.SITH_GROUP_PUBLIC_ID)
         if user.has_perm("core.view_page"):
             return self.all()
-        groups_ids = [g.id for g in user.all_groups]
-        return self.filter(view_groups__in=groups_ids)
+        return self.filter(view_groups__in=user.all_groups)
 
 
 # This function prevents generating migration upon settings change
@@ -1381,7 +1377,7 @@ class PageRev(models.Model):
         return self.page.can_be_edited_by(user)
 
     def is_owned_by(self, user: User) -> bool:
-        return any(g.id == self.page.owner_group_id for g in user.all_groups)
+        return self.page.owner_group_id in user.all_groups
 
     def similarity_ratio(self, text: str) -> float:
         """Similarity ratio between this revision's content and the given text.
diff --git a/election/views.py b/election/views.py
index 1f67ec0d..63cd70d9 100644
--- a/election/views.py
+++ b/election/views.py
@@ -115,7 +115,7 @@ class VoteFormView(LoginRequiredMixin, UserPassesTestMixin, FormView):
         if not self.election.can_vote(self.request.user):
             return False
         return self.election.vote_groups.filter(
-            id__in=[g.id for g in self.request.user.all_groups]
+            id__in=self.request.user.all_groups
         ).exists()
 
     def vote(self, election_data):
@@ -231,7 +231,7 @@ class RoleCreateView(LoginRequiredMixin, UserPassesTestMixin, CreateView):
         if self.request.user.has_perm("election.add_role"):
             return True
         return self.election.edit_groups.filter(
-            id__in=[g.id for g in self.request.user.all_groups]
+            id__in=self.request.user.all_groups
         ).exists()
 
     def get_initial(self):
@@ -265,7 +265,7 @@ class ElectionListCreateView(LoginRequiredMixin, UserPassesTestMixin, CreateView
             .union(self.election.edit_groups.values("id"))
             .values_list("id", flat=True)
         )
-        return not groups.isdisjoint({g.id for g in self.request.user.all_groups})
+        return not groups.isdisjoint(self.request.user.all_groups.keys())
 
     def get_initial(self):
         return {"election": self.election}