The file entity_picker.js takes 20 seconds+ to load for the first response in a vanilla Confluence. The subsequent response is usually fast after it has been cached. This prevents large instances from loading the file due to a timeout.

Step To Replicate

1. Go to > General Configuration > Global Permissions
2. Click search for the Grant browse permission to field for Groups.

Observed Result

The following result takes 20 second to complete even in a newly installed instance.

This bug affect all the features that require entity_picker.js, for example adding restrictions to Team Calendars or Pages.

Workaround

Turning off HTTP compression in > General Configuration > Connection Timeouts may work in some instances.