RENDERLights can be set to various Indirect illumination modes. By default RENDERLights will pre-calculate a fast and basic overall illumination,
this initial illumination is sufficient for most common scenes, especially exterior scenes who relies entirely on Sunlight.
Among this types of Indirect illumination we will find Real time radiosity calculations, baked and Constant ambient Illumination. Choose this modes according to your needs,
the fastest mode will be lightmap baked scene, but there is some steps involved prior to get a good result, like unwrapping and baking,
this can be either very fast or take some calculation power, depending of the level of quality you are after.