I have been told that this happens (or may happen) when temp and maybe even temp job buffers are filled. However I see the problem happening inside Unity API code that has nothing to do with ECS. Can some one please explain it to me? I need to optimize this, all together we are talking about a significant amount of milliseconds (it's not just the following case) with deep profile to see where it happens The amount of time it takes, but this is just one of the cases I have to fix. BTW if the reason why it happens is what I currently believe, I will need to be able to configure the size of these preallocated buffers.