Optimize lighting in the Built-In Render Pipeline

To optimize the lights in your sceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary, avoid Unity using multiple render passes to render GameObjectsThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary, or doing too much work to render lighting. This reduces the number of the draw calls the CPU sends, and the number of vertices and pixelsThe smallest unit in a computer image. Pixel size depends on your screen resolution. Pixel lighting is calculated at every screen pixel. More info
See in Glossary the GPU processes.

Do the following:

• Use lightmapping to light static objects, instead of realtime lightsLight components whose Mode property is set to Realtime. Unity calculates and updates the lighting of Realtime Lights every frame at runtime. No Realtime Lights are precomputed. More info
  See in Glossary.
• Avoid combining meshes if they’re lit by different realtime per-pixel lights, because Unity calculates every light for every combined meshThe main graphics primitive of Unity. Meshes make up a large part of your 3D worlds. Unity supports triangulated or Quadrangulated polygon meshes. Nurbs, Nurms, Subdiv surfaces must be converted to polygons. More info
  See in Glossary.
• Avoid lighting GameObjects with multiple per-pixel lights.

Prioritize lights

To avoid lighting GameObjects with multiple per-pixel lights, prioritize which lights provide per-pixel lighting based on which GameObjects they light.

For example, in a driving game, prioritize the car headlights as a per-pixel light, but deprioritize the rear lights and distant lampposts.

To decrease the number of per-pixel lights, do any of the following:

• In the Light component Inspector window, set Render Mode to Not important. This sets the light as a per-vertex light or spherical harmonics (SH) light.
• In the Quality settings window, decrease Pixel Light Count. This excludes lights from the per-pixel light group.

To increase the number of per-pixel lights, do any of the following:

• In the Light component Inspector window, increase the Intensity. The brightest light is always a per-pixel light.
• In the Light component Inspector window, set Render Mode to Important. This sets the light as a per-pixel light.
• In the Quality settings window, increase Pixel Light Count. This includes more lights in the per-pixel light group.

Disable per-vertex and spherical harmonics (SH) lights

To disable per-vertex and SH lights in a custom shaderA program that runs on the GPU. More info
See in Glossary, add the OnlyDirectional tag to the Pass in your ShaderLabUnity’s language for defining the structure of Shader objects. More info
See in Glossary code. For more information, refer to Pass tags in ShaderLab reference.

Additional resources

• Per-vertex and per-pixel lights
• Per-vertex and per-pixel lights in the Built-In Render Pipeline