Ok, maybe someone else who knows more about the Vulkan integration in UE4 can comment on it :o
The problems I remember were only with the game thread, not the GPU. I am already spawning the destructible mesh the second the mesh got hit by something, so it’s only around if it needs to be. And there’s one little annoying bug with this, the frame the DM is spawned it’s actually invisible. This bug got introduced in 4.8 or 4.9, and you seem to have workarounded it with just switching visibility of regular mesh and DM instead of spawning it, but in my case that does not work. I guess you had GPU perf problems.
For better performance I am also killing the debris immediately and instead spawn my own physics objects there so that I have full control about when and how to fade them out. The problem I have is that I need the “Form Extended Structures” feature enabled, and it causes hitches between 200ms and 1000ms if you spawn one DM with “Form Extended Structures” enabled close to another DM. And hitches of up to 1 second don’t feel that good in a game.
The other huge problem were that once you reach a certain number between 8000 and 9000 fractures in your whole scene, the performance suddenly decreases a lot for a few frames after you added more fractures. And this affects GPU time even more than CPU time. Almost as if there is some hard coded value between 8000 and 9000. The game basically becomes unplayable after you reached that number.