The Android App will download everything it might need for working online. This means that if your user has been assigned lot of programs and Organisation Units it will take long time to download. May I suggest you reduce the amount of metadata by assigning only one OU and one program?
Mine is not taking as long (though it did once during testing) but I came searching on the thread for any recommendations on how to slim down the syncing time.
Is it also possible to not have data sets be part of the configurations and data being synced (going by your suggestion to limit the OUs and Programs accessible to a user).
Sure, @lillian1n2 . The thing is that most of the datasets (at least in our testing servers) are shared publicly (see below) and therefore downloaded on Android. But if you would remove this public sharing it would reduce the amount of data being transfer.