Good to hear that it's at least somewhat better. Zooming and animations don't really matter on the performance here at all. Everything is drawn again every frame, so it doesn't matter if something is drawn on position x or y. That's a bit of a drawback of not having built this on some proper "smart" engine and having my own (limitation coming from the original 13 kilobyte size limit).
You mean that the game would kinda be rotated 90 degrees? Kindle doesn't do rotation like phones do? Might be pretty doable...
And of course I'll still try to optimize it in different ways to run smoother on lower end devices too.