diff --git a/app/models/concerns/has_group_relation_definition.rb b/app/models/concerns/has_group_relation_definition.rb
index 51426aebc..ac376751e 100644
--- a/app/models/concerns/has_group_relation_definition.rb
+++ b/app/models/concerns/has_group_relation_definition.rb
@@ -14,8 +14,7 @@ module HasGroupRelationDefinition
     validates :access, presence: true
     validate :validate_access
 
-    after_save :touch_related
-    after_destroy :touch_related
+    after_commit :touch_related
   end
 
   private
diff --git a/db/migrate/20120101000001_create_base.rb b/db/migrate/20120101000001_create_base.rb
index 6c5d8ce84..7b2125f82 100644
--- a/db/migrate/20120101000001_create_base.rb
+++ b/db/migrate/20120101000001_create_base.rb
@@ -178,6 +178,7 @@ class CreateBase < ActiveRecord::Migration[4.2]
     add_index :groups_users, [:user_id]
     add_index :groups_users, [:group_id]
     add_index :groups_users, [:access]
+    add_index :groups_users, %i[user_id group_id access]
     add_foreign_key :groups_users, :users
     add_foreign_key :groups_users, :groups
 
diff --git a/db/migrate/20220131135531_issue3940_add_index.rb b/db/migrate/20220131135531_issue3940_add_index.rb
new file mode 100644
index 000000000..aa5ec184f
--- /dev/null
+++ b/db/migrate/20220131135531_issue3940_add_index.rb
@@ -0,0 +1,10 @@
+# Copyright (C) 2012-2022 Zammad Foundation, https://zammad-foundation.org/
+
+class Issue3940AddIndex < ActiveRecord::Migration[6.0]
+  def change
+    # return if it's a new setup
+    return if !Setting.exists?(name: 'system_init_done')
+
+    add_index :groups_users, %i[user_id group_id access]
+  end
+end