Command buffers in jobs are generally slow because they can't be bursted. I've got around this so far by: 1) Separating logic out in jobs where possible - although if you still have the command buffer job doing just command buffer stuff it still seems slow. 2) Adding component data changes to a queue/list and delaying until the next frame to use EntityManager to do the work instead on the main thread. Both introduce code bloat though. It would be great if anyone from Unity could give us some estimate as to when EntityCommandBuffer will be support burst...? Do other people have any more ideas or workarounds for command buffer usage?