A container in Unity is a GameObject that holds a bunch of child objects in a group of a similare type and is commonly used in Unity games. In this case we had all spawned vehicles under Entities/Cars. Unity combines all the child object transforms with each root level object in the scene, so adding or removing children, like spawning a vehicle, causes that array of transforms to change and recalculations happen. It is more optimal to just store individual objects in the root and not use containers, but then it is harder to debug a scene with thousands of objects. I have been moving a variety of object types out of containers, like trees, object pools, chunks and now vehicles. Each of these is a small optimization, but added together equals decent gains.
Bloodmoon parties are formed from players near each other. It used to be 30m and now is 80m, which make a lot more sense, since two players could be on the opposite sides of a large base when the blood moon starts and it would be sending separate groups of enemies at each. These parties are not recalculated when you move around, so it needs to be correct at the start of BM.