Installed card is:
Samsung EVO Select. Specs are
I have deleted and reinstalled Gaia along with all my maps. Quite the chore to start over. I am now going to try downloading one at at time. I started with NPS visitor map of Death Valley. It's downloading markedly faster than prior to the reinstall. I will do the gaia topo next to see how that one does. There is either a problem when you send multiple downloads at once (regardless of the fact that the app only downloads one map at a time) or once you have downloaded numerous maps and gaia has been installed for some period of time it simply doesn't work as it should. I'll update this thread if I get any new information.
- Up to 100MB/s & 90MB/s read & write speeds respectively; Class 10 UHS 3
I know the goal has always been get a tablet with low storage and make it a tablet with lots of storage via an SD Card. It seems sometimes this works and sometimes it doesn't. I can't speak to any specifics with Gaia. It's why I run a tablet with large internal storage. Yes, it happens to be an iPad. Your research sounds useful for the Android folks.
This article sheds a little light on the fastest cards available. https://www.digitaltrends.com/mobile/best-microsd-cards/