Revolution engine lighting system is something that makes me feel proud. It can light objects in a very realistic manner and is very extensible. However, it's very slow since it's all software based, almost all calculations (except for some blending between layers and a couple of things more) are done by software. This decision was made because wii hardware lighting system doesn't work right in homebrew, and if I wanted to have a realistic lighting system, I had to write it.
But, after all, not All of the hardware is working bad, so some parts of the lighting system can be ported to hardware.
And that's what I'm doing: port everything I can from software to hardware (and it's working quite well). Remember that 8% speed boost from 0.5 to 0.5.1? well, now I expect about a 30-40% speed boost :)