> But my advice: do not count on anything refreshing ever. Do not have animations, or transitions. Preload things to the correct spaces, then fill in. Reserve fixed white areas for output, and then fill in with black. (This works much better than the reverse!)

I would ammend to this that if you have an operation that can't complete quickly, it's better to have some kind of animation, even if it's notably slower than the already-slow screen refresh so that the user can tell that there's something happening.