As stated, 3 mouse patches are disabled in my build. they are in source archive, just uncomment lines in debian/patch/series. i disabled them as in the game i tested it caused an offset to clicks.

dosbox turbo seems to have extra config option for gpu rendering according to sites performance page. i've seen some talk about replacing drawing code on pi with gl calls. at the moment, from what i've read, it renders to texture in sdl and then displays on screen. there may be some gain in direct rendering, maybe not.