These all are what I did for Gotham Knights 4 years ago in UE4. Actually I did a lot more stuff; such as incremental render state updates, parallel AddToWorld / RemoveFromWorld, BodyInstance sharing... etc
Kinda glad what I contributed to Gotham Knights are proved still useful and yet done in Epic side.
https://portal.productboard.com/epicgames/1-unreal-engine-public-roadmap/tabs/94-forward-looking