I have an unencrypted database with about 100,000 science articles (mainly stuff from RSS feeds). I added it to my iPhone’s DTTG (latest version) last night before bed, and I’m now 9 hours into the initial sync. It’s almost finished. Although I set it to “Download files: On demand”, I’m watching individual article names slowly scroll by.
I don’t hugely mind - although I’m kind of dreading going through it again tonight for my iPad - but thought you’d want to know.
Relatedly, deleting databases from DTTG doesn’t seem to work for me. I can reliably reproduce this:
 Go into Locations > Personal (my sync store) and enable a small database with maybe 50 text items. Watch it sync.
 Change my mind: I don’t want that. Deselect the sync. Back on the main screen, left-swipe the database and tap Delete. Confirm it.
[*] Go back into Locations > Personal. That database status is “Being deleted”. From what I can tell, no amount of time or tapping about can get it back to status “Remote” like the other unsynced databases. To get out of that state, I have to uninstall and reinstall DTTG.
The sync completed successfully. I can now access all my science stuff from the road. Yay!
Also, my phone is hot, presumably from processing 100,000 items more deeply than I would have expected it to.
Also also, I’ve confirmed that it didn’t download the items. I still have to manually download each item when I want to access it. That’s the correct and desired behavior, but it did take 11 hours to fetch and process the metadata for the articles that it didn’t actually download.
In general I have found this to be slow, but it does eventually finish! I’m not sure why a database of about 50 items would take so long, but my databases of about 200, and about 5000 items both took quite a while (the 5000 database taking considerably longer).
I’m also not so sure the extent to which those processes (of deleting a database) continue once the app is no longer on screen or if the device is asleep. iOS is pretty aggressive at killing most background processes within a few seconds, so a lengthy deletion might not proceed continuously in the background, making it seem like it’s taking considerably longer (because, in fact, it isn’t happening at all). I’m sure someone from DEVONtech can clarify.