[Skyld]

The sync distance is indeed useful on iPhone because the client is not aware of any players outside of the sync distance, therefore there is less network processing to do. Beforehand it was using a huge amount of CPU time on iPhone just to process all the packets coming in. Typically on iPhone we are using a sync distance near to that of the visible on-screen area so that you only get updates for players that you can see.

The sync distance always applies on GMAPs, and as the list shows, it is optional for inside levels. I think you need to restart the gserver for this option to take correct effect without causing issues.