The method which I’ve mentioned is just simple layerMask - https://playground.babylonjs.com/#0LYEC3#4
What I meant is that for minimap you need to render dynamically only user marker (which is not rendered by the main camera, so the number of draw calls will be actually the same).
Then, depending on your application, you may add either the second oversimplified version of the model in vertical projection, or even use appropriate static image in a viewport’s layer background, as in @sebavan example from another thread).