Create a Course and annotate its course id. Create 10 groups with long group name (Ex: BA/BSc (Hons) Open degree (QD) qualification, ...) and annotate their group ids. Install the attached  generate_user.php  @ admin/cli. Invoke the script like this, ten times, using the annotated course id with a different group id on each execution. php admin/cli/generate_user.php -t=10000 -c=courseid -g=groupid Go to Course Participant page. Verify that you can see a list of users without any error. Both without filters ((there should be 50000 users enrolled) and filtering by any of the groups (there should be 10000 users on each).   P/S: I created a CLI file that will generate, enrol, assign to a group to test this ticket. If you want to use, please refer attachment (Copy to admin/cli)