Thank you for your additional posts regarding memory usage with SD cards. When it comes to SD cards, there is often a certain amount of space that is used for system loading, as well as the SD card partitions as you mention. Similar to a device hard drive, you never truly get the space they say you are going to get. In regards to Avenza Maps and caching of data, when you process custom made maps from an external source, such as an SD card, the map processes into a series of tiles for use in the app. This processing takes your original file size and will expand it significantly resulting in a larger file size taking up space. Unfortunately, in order to have maps usable in the app, this is unavoidable. Once the maps are loaded into a Collection, you will still need to maintain the maps folder on the SD card as this is holding the processed maps that the app is referencing. If you remove any processed contents from the SD card (or remove the SD card), they will no longer work in the app and you will need to start over.
As you mention you are using an SD card with over 800 maps on it – this is a significant amount of data that can cause processing, memory and general performance issues. Are all of these maps stored within the app as well? The issue at hand may not be the SD card itself, but the CPU, RAM (depending on which model you have, Samsung Tab A’s generally only have 1.5-2GB of RAM), and processing capabilities of your mobile device instead, as regardless of the source of the files, it is the one that is going all the heavy lifting so to speak.
Please feel free to contact our Support team directly (help.avenzamaps.com) and we would be happy to answer any further questions you may have.