diff --git a/zerver/lib/import_realm.py b/zerver/lib/import_realm.py
index e42271183e..c7df38ac3f 100644
--- a/zerver/lib/import_realm.py
+++ b/zerver/lib/import_realm.py
@@ -247,11 +247,15 @@ def fix_upload_links(data: TableData, message_table: TableName) -> None:
                     )
 
 
-def fix_stream_permission_group_settings(data: TableData, realm: Realm) -> None:
+def fix_stream_permission_group_settings(
+    data: TableData, system_groups_name_dict: dict[str, NamedUserGroup]
+) -> None:
     table = get_db_table(Stream)
     for stream in data[table]:
         for setting_name in Stream.stream_permission_group_settings:
-            stream[setting_name] = get_stream_permission_default_group(setting_name, realm)
+            stream[setting_name] = get_stream_permission_default_group(
+                setting_name, system_groups_name_dict
+            )
 
 
 def create_subscription_events(data: TableData, realm_id: int) -> None:
@@ -1269,9 +1273,9 @@ def do_import_realm(import_dir: Path, subdomain: str, processes: int = 1) -> Rea
 
         # We expect Zulip server exports to contain these system groups,
         # this logic here is needed to handle the imports from other services.
-        role_system_groups_dict: dict[int, NamedUserGroup] | None = None
+        system_groups_name_dict: dict[str, NamedUserGroup] | None = None
         if "zerver_usergroup" not in data:
-            role_system_groups_dict = create_system_user_groups_for_realm(realm)
+            system_groups_name_dict = create_system_user_groups_for_realm(realm)
 
         # Email tokens will automatically be randomly generated when the
         # Stream objects are created by Django.
@@ -1289,11 +1293,11 @@ def do_import_realm(import_dir: Path, subdomain: str, processes: int = 1) -> Rea
             creator_id = stream.pop("creator_id", None)
             stream_id_to_creator_id[stream["id"]] = creator_id
 
-        if role_system_groups_dict is not None:
+        if system_groups_name_dict is not None:
             # Because the system user groups are missing, we manually set up
             # the defaults for stream permission settings for all the
             # streams.
-            fix_stream_permission_group_settings(data, realm)
+            fix_stream_permission_group_settings(data, system_groups_name_dict)
         else:
             for setting_name in Stream.stream_permission_group_settings:
                 re_map_foreign_keys(data, "zerver_stream", setting_name, related_table="usergroup")
@@ -1540,8 +1544,8 @@ def do_import_realm(import_dir: Path, subdomain: str, processes: int = 1) -> Rea
     # We expect Zulip server exports to contain UserGroupMembership objects
     # for system groups, this logic here is needed to handle the imports from
     # other services.
-    if role_system_groups_dict is not None:
-        add_users_to_system_user_groups(realm, user_profiles, role_system_groups_dict)
+    if system_groups_name_dict is not None:
+        add_users_to_system_user_groups(realm, user_profiles, system_groups_name_dict)
 
     if "zerver_botstoragedata" in data:
         re_map_foreign_keys(
@@ -2078,7 +2082,7 @@ def import_analytics_data(realm: Realm, import_dir: Path, crossrealm_user_ids: s
 def add_users_to_system_user_groups(
     realm: Realm,
     user_profiles: list[UserProfile],
-    role_system_groups_dict: dict[int, NamedUserGroup],
+    system_groups_name_dict: dict[str, NamedUserGroup],
 ) -> None:
     full_members_system_group = NamedUserGroup.objects.get(
         name=SystemGroups.FULL_MEMBERS,
@@ -2086,6 +2090,11 @@ def add_users_to_system_user_groups(
         is_system_group=True,
     )
 
+    role_system_groups_dict: dict[int, NamedUserGroup] = dict()
+    for role in NamedUserGroup.SYSTEM_USER_GROUP_ROLE_MAP:
+        group_name = NamedUserGroup.SYSTEM_USER_GROUP_ROLE_MAP[role]["name"]
+        role_system_groups_dict[role] = system_groups_name_dict[group_name]
+
     usergroup_memberships = []
     for user_profile in user_profiles:
         user_group = role_system_groups_dict[user_profile.role]
diff --git a/zerver/lib/streams.py b/zerver/lib/streams.py
index 3ebb4ba9b6..93c8d21c51 100644
--- a/zerver/lib/streams.py
+++ b/zerver/lib/streams.py
@@ -25,6 +25,7 @@ from zerver.lib.timestamp import datetime_to_timestamp
 from zerver.lib.types import AnonymousSettingGroupDict, APIStreamDict
 from zerver.lib.user_groups import (
     get_group_setting_value_for_api,
+    get_role_based_system_groups_dict,
     user_has_permission_for_group_setting,
 )
 from zerver.models import (
@@ -139,20 +140,19 @@ def send_stream_creation_event(
     send_event_on_commit(realm, event, user_ids)
 
 
-def get_stream_permission_default_group(setting_name: str, realm: Realm) -> UserGroup:
+def get_stream_permission_default_group(
+    setting_name: str, system_groups_name_dict: dict[str, NamedUserGroup]
+) -> UserGroup:
     setting_default_name = Stream.stream_permission_group_settings[setting_name].default_group_name
-    return NamedUserGroup.objects.get(
-        name=setting_default_name,
-        realm=realm,
-        is_system_group=True,
-    )
+    return system_groups_name_dict[setting_default_name]
 
 
 def get_default_group_setting_values(realm: Realm) -> dict[str, UserGroup]:
     group_setting_values = {}
+    system_groups_name_dict = get_role_based_system_groups_dict(realm)
     for setting_name in Stream.stream_permission_group_settings:
         group_setting_values[setting_name] = get_stream_permission_default_group(
-            setting_name, realm
+            setting_name, system_groups_name_dict
         )
 
     return group_setting_values
@@ -179,13 +179,18 @@ def create_stream_if_needed(
 
     group_setting_values = {}
     request_settings_dict = locals()
+    # We don't want to calculate this value if no default values are
+    # needed.
+    system_groups_name_dict = None
     for setting_name in Stream.stream_permission_group_settings:
         if setting_name not in request_settings_dict:  # nocoverage
             continue
 
         if request_settings_dict[setting_name] is None:
+            if system_groups_name_dict is None:
+                system_groups_name_dict = get_role_based_system_groups_dict(realm)
             group_setting_values[setting_name] = get_stream_permission_default_group(
-                setting_name, realm
+                setting_name, system_groups_name_dict
             )
         else:
             group_setting_values[setting_name] = request_settings_dict[setting_name]
diff --git a/zerver/lib/user_groups.py b/zerver/lib/user_groups.py
index 2946b85526..f73c695c6f 100644
--- a/zerver/lib/user_groups.py
+++ b/zerver/lib/user_groups.py
@@ -868,12 +868,11 @@ def bulk_create_system_user_groups(groups: list[dict[str, str]], realm: Realm) -
 
 
 @transaction.atomic(savepoint=False)
-def create_system_user_groups_for_realm(realm: Realm) -> dict[int, NamedUserGroup]:
+def create_system_user_groups_for_realm(realm: Realm) -> dict[str, NamedUserGroup]:
     """Any changes to this function likely require a migration to adjust
     existing realms.  See e.g. migration 0382_create_role_based_system_groups.py,
     which is a copy of this function from when we introduced system groups.
     """
-    role_system_groups_dict: dict[int, NamedUserGroup] = {}
 
     system_groups_info_list: list[dict[str, str]] = []
 
@@ -906,9 +905,6 @@ def create_system_user_groups_for_realm(realm: Realm) -> dict[int, NamedUserGrou
     bulk_create_system_user_groups(system_groups_info_list, realm)
 
     system_groups_name_dict: dict[str, NamedUserGroup] = get_role_based_system_groups_dict(realm)
-    for role in NamedUserGroup.SYSTEM_USER_GROUP_ROLE_MAP:
-        group_name = NamedUserGroup.SYSTEM_USER_GROUP_ROLE_MAP[role]["name"]
-        role_system_groups_dict[role] = system_groups_name_dict[group_name]
 
     # Order of this list here is important to create correct GroupGroupMembership objects
     # Note that because we do not create user memberships here, no audit log entries for
@@ -982,7 +978,7 @@ def create_system_user_groups_for_realm(realm: Realm) -> dict[int, NamedUserGrou
     GroupGroupMembership.objects.bulk_create(subgroup_objects)
     RealmAuditLog.objects.bulk_create(realmauditlog_objects)
 
-    return role_system_groups_dict
+    return system_groups_name_dict
 
 
 def get_system_user_group_for_user(user_profile: UserProfile) -> NamedUserGroup:
diff --git a/zerver/views/streams.py b/zerver/views/streams.py
index 60da8c9cff..19c69fa79b 100644
--- a/zerver/views/streams.py
+++ b/zerver/views/streams.py
@@ -81,6 +81,7 @@ from zerver.lib.user_groups import (
     GroupSettingChangeRequest,
     access_user_group_for_setting,
     get_group_setting_value_for_api,
+    get_role_based_system_groups_dict,
     parse_group_setting_value,
     validate_group_setting_value_change,
 )
@@ -594,6 +595,9 @@ def add_subscriptions_backend(
     setting_groups_dict = {}
     group_settings_map = {}
     request_settings_dict = locals()
+    # We don't want to calculate this value if no default values are
+    # needed.
+    system_groups_name_dict = None
     for setting_name, permission_configuration in Stream.stream_permission_group_settings.items():
         assert setting_name in request_settings_dict
         if request_settings_dict[setting_name] is not None:
@@ -607,8 +611,10 @@ def add_subscriptions_backend(
             )
             setting_groups_dict[group_settings_map[setting_name].id] = setting_value
         else:
+            if system_groups_name_dict is None:
+                system_groups_name_dict = get_role_based_system_groups_dict(realm)
             group_settings_map[setting_name] = get_stream_permission_default_group(
-                setting_name, realm
+                setting_name, system_groups_name_dict
             )
             setting_groups_dict[group_settings_map[setting_name].id] = group_settings_map[
                 setting_name