As I promised some weeks ago, here are the results of our take on optimizing a SDL game (Tennix) for the Maemo devices. All other platforms on which Tennix runs obviously also profit from these optimizations. The presentation with all the details is available here: Optimizing an open source game for mobile devices (PDF). I also have two videos for you: Tennix running on a tablet before and after the optimizations.
Conclusions: Do profile (using oprofile or gprof) your applications to find bottlenecks. Look at callgraphs (using graphviz) to determine function usage. Most of the time, small code changes result in big performance boosts. Some Maemo-specific hints for SDL development are available in Game development in the Maemo Wiki.
The optimized release of Tennix (0.7.0) is available in Maemo Extras already. Go get it! :)