Performance issue with bulk organize examiners menu

[torgeirl]

On an assignment, admins can navigate the following path to organize examiners:

1. Manage examiners (/devilry_admin/assignment/{roleid}/examineroverview/)
2. Bulk organize examiners (/devilry_admin/assignment/{roleid}/bulk_organize_examiners/)
3. Select one:
   • Organize examiners randomly (/devilry_admin/assignment/{roleid}/bulk_organize_examiners/random/)
   • Manually add examiners (/devilry_admin/assignment/{roleid}/bulk_organize_examiners/manual-add/)
   • Manually replace examiners (/devilry_admin/assignment/{roleid}/bulk_organize_examiners/manual-replace/)

For our larger courses, the first menu (1.) can be a little slow while the second (2.) in the extreme cases will timeout (HTTP 504).

As a workaround, the paths to the next menu items (3.) can be entered manually. This leads me to believe there is performance bug with the view for /devilry_admin/assignment/{roleid}/bulk_organize_examiners/.