Preload project, user and group to reuse objects

lib/gitlab/import_export/relation_factory.rb

@@ -34,6 +34,8 @@ module Gitlab
 
       PROJECT_REFERENCES = %w[project_id source_project_id target_project_id].freeze
 
+      GROUP_REFERENCES = %w[group_id].freeze
+
       BUILD_MODELS = %i[Ci::Build commit_status].freeze
 
       IMPORTED_OBJECT_MAX_RETRIES = 5.freeze
@@ -89,7 +91,13 @@ module Gitlab
 
         setup_models
 
-        generate_imported_object
+        object = generate_imported_object
+
+        # We preload the project, user, and group to re-use objects
+        object = preload_keys(object, PROJECT_REFERENCES, @project)
+        object = preload_keys(object, GROUP_REFERENCES, @project.group)
+        object = preload_keys(object, USER_REFERENCES, @user)
+        object
       end
 
       def self.overrides
@@ -122,6 +130,19 @@ module Gitlab
         remove_encrypted_attributes!
       end
 
+      def preload_keys(object, references, value)
+        references.each do |key|
+          setter = "#{key.delete_suffix('_id')}=".to_sym
+          next unless object.respond_to?(key) && object.respond_to?(setter)
+
+          if object.public_send(key) == value&.id
+            object.public_send(setter, value)
+          end
+        end
+
+        object
+      end
+
       def update_user_references
         USER_REFERENCES.each do |reference|
           if @relation_hash[reference]