kouteiheika

Have you ever considered making the UI external to the game, so that somebody else could take care of it while you'd be able to fully concentrate on the simulation aspect itself? By external I mean - export appropriate API to control the game, and import a few symbols from the UI SO/DLL so that the game would be able to interact with it. Considering the fact that the game already reacts to the user input (hence you have those entry points that need to be exported already well defined) creating such interface should be only a matter of finding the time to do it.

The community has already proven that they have the ability to deliver superior UI (Stonesense, Dwarf Therapist, numerous tilesets, etc.), so why won't you leave it to them? There are limits to what one can do with memory hacking; a real API would make it possible to make something like Stonesense, but fully interactive. Wouldn't that be awesome?

If you aren't doing using it already, when it comes to performance you should look into PGO as that may give you a fairly nice performance boost for free. (In more extreme cases I've seen up to 70%~80% gain for calculation-heavy code.) Basically, you build DF with PGO profiling enabled, then you fire up the game and load a map which suffers from FPS death, let it run for a minute, quit, and then you recompile everything with profiling data that was generated. I definitely recommend you to try and see if there will be any difference.

If you're going to try to sell it consider dual licencing it under a commercial licence and GPL; that way all of the free software projects can benefit from it while you'll still get paid.