[curt.clifton]

You should email the support ninjas: from inside OF, choose Help -> Send Feedback. This is not normal behavior and I suspect indicates that your database is bloated from having sync turned on but not synchronizing your devices frequently enough. (OF has to store every single change to the data separately until it is sure that all synchronized devices have received all changes.)

But I'm just guessing. The support ninjas will help you work through it.