Rendering the graphics is pretty inconsequential in terms of performance -- especially as fast forward speed gets higher, running the actual code for all the entities in the game takes more and more of the resources while rendering stays pretty flat. It *does* technically take more resources to render the whole map zoomed out than it does to render a smaller window so if you want to get basically as close as you can to what you're suggesting, just zoom all the way in so you can see just a tiny portion of the map -- it might get you stable framerates on, for example, 5x instead of 4x, but won't be a total game-changing difference.