In this post, I will define a section of light rendering.

There is three type of light rendering:

1. Real-time: This type of rendering update each frame so it is useful for moving character or other moving objects.
   
2. Baked GI (Global Illumination) Lighting: with this approach, the lightmap will bake. this means all lights – including direct light which come from Direction light and the indirect light which is bounced from other objects – on static objects are written to a texture which overlaid on the top of scene geometry to create the effect of lighting. So it will calculate once and will increase the performance, but we lose the ability to move the light in the scene.
   
3. Precomputed Realtime GI Lighting: the problem is by baking light on static objects we will unable to react to changing the light. Precomputed lighting has some solution for that:
   

it will calculate GL and bounced light which response to light changing in real-time. Day system is a good example of this technique, where position and color of light source change over time.

In Ordibehesht Studio, we are using the second method in developing 4wheleers (our last game) and performance has increased for this mobile game.

references :

Unity – Lighting & Rendering