Bringing up the user list under Manage/User takes extremely long when there is a large number of objects (> 1M) in the repo.
The reason for this is apparently that the query sent by the UI includes the _sortKeys option by default, meaning that the repo needs to sort several millions of entries in order to just display the first page.
This turns extreme when DS is used as a repo, which treats the query as unindexed due to the amount of results. In that case, IDM appears to switch to client-side sorting, during which it silently fails, i.e. the query never returns any results at all.
To fix this, I've tried the simple hack of changing the last line in
which makes IDM effectively ignore the sorting parameter. As a result, the user list comes up right away; unsorted, but no administrator ever wants to see the first 50 out of millions of users anyway.
There should be an option to make the sorting optional, otherwise working with large data sets becomes painful and gives the user the impression that IDM as a system is slow or operating at limits.