To resolve this issue in patch 6 and above, there's a new Business Rule available in Config > Business Rules > Event Options:
- Classic loading, sorting will work: Choose this option for general use of the Events module if no performance issues have been encountered.
- Fast loading, but sorting will not work: Choose this option if users have encountered performance issues with events in your database. May be useful for large events, or if multiple users need to access an event record at the same time (such as with the Mobile Event App). Note: this option disables sorting of the participant list in events.