Physics changes a lot, especially if you have a physics controlled player (a car), or other gameplay sensitive objects.
I've simply added a member variable: public bool sendQuickly = false; to the TNSyncRigidbody script, and then called SendQuickly instead of Send if the sendQuickly member variable is true.
This way the user can choose per rigidbody: is this object getting moved a lot by physics? Perhaps I should check the sendQuickly bool.