That's Quake2, not Quake3. And the loader is most likely written in C, because it's a port from the orginial sources. I'm not sure if it's worth to bother with that. Apart from that, the bsp structure isn't exactly what jPCT needs, so you have to convert this anyway or live with inferior performance. That said, the usual limitations of Android apply here, i.e. polygon count shouldn't go through the roof or otherwise, it will be slow at least on everything but the high end. You can try An3DBench from the market. That last benchmark is a converted, pretty basic Quake3 level. That's the performance you are about to get on your device for rendering alone.