I have reported our experimentals to the original authors, so at least they now know game has broader audience than desktops.

I have done some SDL programming, but I do not know what is the root cause of choppiness.

Game uses SDL_PollEvent , where I think SDL_WaitEvent is better. I tested with WaitEvent, but other architecture is designed for polling, so e.g. audio is played a little bit only when user press key (-> not playable).

How about smaller resolution? Anybody tried that?

Audio can be bottleneck, binary is linked to the:
libopenal.so.1
libvorbisfile.so.3
libmodplug.so.1
libasound.so.2
libpulse-simple.so.0
libpulse.so.0
libvorbis.so.0
libogg.so.0
libpulsecommon-0.9.15.so

It seems that all audio is in ogg-format.