1 - enter real-time mode
2 - enter precomputation mode
i/o - Using raytracing precomputed texture off/on
P while in precomputation (2) mode - save texture to fille
drag'n'drop file to app - load texture from file
When you open the app, simple (1 bounce) real time lighting is used.
Next, press 2 to switch to the precomputation mode, wait about 1 minute and press 1 to return back.
Now you can press o and enable using precomputed luminance information from texture!