FYI: Our latest code should use considerably less RAM (don't know how relevant this is for maemo devices) and be faster. We (GemRB dev team) are planning a new release (0.6.2) a week or so from now.

If you're using OpenAL Soft like the other handheld ports then it seems to be slow and FP-intensive - not something we can do an awful lot about - so if these devices lack an FPU I'd suggest someone tries our SDLAudio plugin once we release (the version in git right now is still buggy).