Slow loading of route `courses` for root

[tgloeggl]

Version
3.28

Describe the bug
All courses with active OC plugin are listed. This takes for large installations and for the root-users up to 10 secondes. It happens in the background, though it is not to bad currently

Expected behavior
Find out how to improve on that

[ferishili]

Hi @tgloeggl
according to what we have discussed, I would say, the title is incorrect and should be contents instead of courses!