CullScriptable process time increases when decreasing Field of View

Terrain: Fixes excessive CPU use with terrains when using a narrow field of view. Adds a new 'heightmapMinimumLODSimplification' property to terrains to set the minimum level of detail required on a terrian.

This bug has been addressed in Unity 2023.1 onwards. Unfortunately the nature of the fix involves a change in the behavior of terrain that could require some user intervention. As such it does not seem like a good candidate for backporting to an LTS release.

This bug has been addressed in Unity 2023.1 onwards. Unfortunately the nature of the fix involves a change in the behavior of terrain that could require some user intervention. As such it does not seem like a good candidate for backporting to an LTS release.