Our company has now used ThinkGeos Xamarin Forms solution for a year. We use the WMTS_Overlay functionality, along with a lot of custom functionality.
The IOS version is very quick and stable now, however the Android version still lacks speed in tile loading, and it crashes alot when moving around the map. Se video below for an example of slowness. Obviously, something has to be wrong with the tile loading algorithm, with using up to 30 seconds loading a map screen on WIFI. As said, it is not this slow on IOS, so something can surely be done about this? We reported this bug last spring, and ThinkGeo speeded it up somewhat. We had hoped that they would thoroughly fix this for 2018, but it has not been done.
Another error yet to be fixed even though we reported this in 2017 is that we actually get an "Out of Memory" error when moving around the map. This causes our application to crash often, giving the users of our application a bad map experience.
These are two huge bugs that we as said reported in 2017, but that never got solved properly. Is this something you plan to fix in 2018 ThinkGeo?