von Anton Tremetzberger.
Hello Eva,
The reason for the slow loading of the question collection could be that in certain (mostly older) Moodle versions, the questions are duplicated.
You can find information about this in the quiz forum (eg https://moodle.org/mod/forum/discuss.php?d=469704). There are now scripts available to help you delete the duplicates. We are also having problems with the duplicates and we will try to eliminate them with scripts in the next few weeks.
Maybe this could also the reason why no course backup emails are being sent.
br, Anton