Unittest The changes are covered by numerous existing unit tests. The patch only offers an optimisation of existing code and does not include any new functionalities. Run the whole Unit-Test-Suite UI test: Create a new course with multiple activities Work in the activities Delete course Expectations of the Surface Test The course will be deleted. To test the Performance Impact Especially for very large instances, with 100,000+ courses and several million activities, this optimization leads to a significant performance increase. I.e. for tests a large number of courses with activities would have to be created. For small instances, the optimization is hardly measurable. Create 20.000 Courses with 10 activities each.  Create 100.000 Users and enrol 50 of them to each course. Create also some activity/course completions -> work in several, ideal in all courses with all users. Delete one course in synchroneous (traditional) mode. Delete one course in background mode. Expectation: The synchronous delete takes a very long time, and exceeds the server timeout (2 minutes) in some cases. The async deletion works.