We have a number of Skeletal Meshes used throughout the level. They don’t move or tick unless the player interacts with them. However, I’ve noticed that their BLAS gets updated every frame even if the animation and skin cache aren’t updated. This adds over 1ms to our update time.
The only exception is if the skeletal mesh is set to `bRenderStatic`, which of course puts the mesh in ref pose. But we want to have it retain the pose that was set. Exporting the posed mesh as a static mesh isn’t an option either since we want them to ragdoll and respond to player interaction.
Are there plans to change the behavior to update the BLAS only when the skin cache is updated? If not, can you suggest what code changes should be done at our end. From a cursory look, it looked like an involved effort and I want do avoid future code conflicts with engine integration.
In my test scene, setting MinUpdatesSinceLastBuildto 0and MaxPrimitivesPerFrame to 100reduced the Updated BL AS stat to 0. You can find a bit more info on these in [this [Content removed]
If this is not what you are looking for, please let me know and I can pass your request to a subject matter expert at Epic.
Hi Sam, thanks for getting back. Those settings are good to know, however they basically control how to balance between rebuild and refit (update) of the BLAS. I was more so looking for a way to avoid both of those altogether (preferably on a per component basis) unless required.
Apologies for the delay, this does look like a situation where the BLAS shouldn’t be updated every frame. I’ve created the following issue for tracking which should be made public soon Unreal Engine Issues and Bug Tracker (UE\-358780)
Also, Epic will be on holiday break starting next week (Dec 22, 2025) and ending Jan 5, 2026 and there will be no responses from Epic on public or private tickets, though you may receive replies from the community on public tickets.