Unity Game Optimization - Third Edition

Using static colliders appropriately

As mentioned previously, the physics engine automatically generates two separate data structures to contain static colliders separately from dynamic colliders. Unfortunately, if new objects are introduced into the static collider data structure at runtime, then it must be regenerated, similar to calling StaticBatchingUtility.Combine() for static batching. This is likely to cause a significant CPU spike. This makes it vital that we avoid instantiating new static colliders during gameplay.

Also, merely moving, rotating, or scaling static colliders triggers this regeneration process and should be avoided. If we have colliders that we wish to move around without physically reacting to other objects colliding ...