diff --git a/invenio_communities/requests/user_moderation/actions.py b/invenio_communities/requests/user_moderation/actions.py
index 4a09cb051..ee1645f8b 100644
--- a/invenio_communities/requests/user_moderation/actions.py
+++ b/invenio_communities/requests/user_moderation/actions.py
@@ -7,60 +7,39 @@
 # it under the terms of the MIT License; see LICENSE file for more details.
 """Communities user moderation actions."""
 
-from collections import defaultdict
-
 from invenio_access.permissions import Identity, system_identity
+from invenio_db import db
 from invenio_i18n import lazy_gettext as _
 from invenio_pidstore.errors import PIDDoesNotExistError
+from invenio_records_resources.services.uow import TaskOp
+from invenio_search.api import RecordsSearchV2
 from invenio_search.engine import dsl
 from invenio_vocabularies.proxies import current_service as vocab_service
 
-from invenio_communities.communities.records.systemfields.deletion_status import (
-    CommunityDeletionStatusEnum,
-)
 from invenio_communities.proxies import current_communities
 
 from .tasks import delete_community, restore_community
 
 
-def _get_communities_for_user(user_id):
-    """Helper function for getting all communities with the user as the sole owner.
-
-    Note: This function performs DB queries yielding all communities with the given
-    user as the sole owner (which is not hard-limited in the system) and performs
-    service calls on each of them. Thus, this function has the potential of being a very
-    heavy operation, and should not be called as part of the handling of an
-    HTTP request!
-    """
-    comm_cls = current_communities.service.record_cls
-    comm_model_cls = comm_cls.model_cls
+def get_user_communities(user_id, from_db=False):
+    """Helper function for getting all communities with the user as the sole owner."""
     mem_cls = current_communities.service.members.record_cls
     mem_model_cls = mem_cls.model_cls
 
-    # collect the owners for each community
-    comm_owners = defaultdict(list)
-    for comm_owner in [
-        mem_cls(m.data, model=m)
-        for m in mem_model_cls.query.filter(mem_model_cls.role == "owner").all()
-    ]:
-        comm_owners[comm_owner.community_id].append(comm_owner)
-
-    # filter for communities that are owned solely by the user in question
-    relevant_comm_ids = [
-        comm_id
-        for comm_id, owners in comm_owners.items()
-        if len(owners) == 1 and str(owners[0].user_id) == user_id
-    ]
-
-    # resolve the communities in question
-    communities = [
-        comm_cls(m.data, model=m)
-        for m in comm_model_cls.query.filter(
-            comm_model_cls.id.in_(relevant_comm_ids)
-        ).all()
-    ]
-
-    return communities
+    if from_db:
+        query = db.session.query(mem_model_cls.community_id).filter(
+            mem_model_cls.user_id == user_id,
+            mem_model_cls.role == "owner",
+        )
+        return (row[0] for row in query.yield_per(1000))
+    else:
+        search = (
+            RecordsSearchV2(index=mem_cls.index._name)
+            .filter("term", user_id=user_id)
+            .filter("term", role="owner")
+            .source(["community_id"])
+        )
+        return (hit["community_id"] for hit in search.scan())
 
 
 def on_block(user_id, uow=None, **kwargs):
@@ -83,9 +62,14 @@ def on_block(user_id, uow=None, **kwargs):
     except PIDDoesNotExistError:
         pass
 
-    # soft-delete all the communities of that user (only if they are the only owner)
-    for comm in _get_communities_for_user(user_id):
-        delete_community.delay(comm.pid.pid_value, tombstone_data)
+    for comm in get_user_communities(user_id):
+        uow.register(
+            TaskOp(
+                delete_community,
+                pid=comm.pid.pid_value,
+                tombstone_data=tombstone_data,
+            )
+        )
 
 
 def on_restore(user_id, uow=None, **kwargs):
@@ -98,8 +82,8 @@ def on_restore(user_id, uow=None, **kwargs):
     user_id = str(user_id)
 
     # restore all the deleted records of that user
-    for comm in _get_communities_for_user(user_id):
-        restore_community.delay(comm.pid.pid_value)
+    for comm in get_user_communities(user_id):
+        uow.register(TaskOp(restore_community, pid=comm.pid.pid_value))
 
 
 def on_approve(user_id, uow=None, **kwargs):