...

You may not be able to use those keys all the time therefore if you desire sorted results, a good practice would be to always add a Sort macro (Boolean Sort, Natural Sort, Number Sort, Date  Date Sort, and Text Sort) within one of the Reporter macros (Combining Reporter, Content Reporter, Expanding Reporter, Grouping Reporter, Local Reporter, Space Reporter, User Group Reporter, and User Reporter).

Use filters in nested reporter macros when using Combining Reporter for more efficient queries

...

The User Reporter macro is a powerful tool that can be used to retrieve and report on Confluence users based on their space permissions, user groups, or usernames. However, as the number of users in the Confluence instance increases and as more external user directories are connected, broad usage of the macro with no filters will increasingly tax the instance’s resources. Here are some general best practice guidelines to get the best performance out of a User Reporter report:

...