After investigation, the asset is not rebuild, what took time is the 2 following part

  1. The serialization of the DDC where we have to initialize the morph targets
  2. E:\P4\main\Engine\Source\Runtime\Engine\Private\SkeletalMeshLODRenderData.cpp DivideAndConquerPermuations function use in the initResources of the render data

I use a GDC demo mesh with ~3100 morph target and it take

  1. Applying the DDC cache: 40 seconds 
  2. creation of render data (InitResources): 65 seconds

I'll investigate on how I can improve the performance of those 2 parts

Steps to Reproduce

Import a skeletalmesh containing a lot of morph target

change UMaterial point by one of the material slot.


RESULT: It take some time to change the UMaterialInstance because the skeletalmesh get rebuild.

EXPECTED: The skeletalmesh should not be rebuild when we change the UMaterialInstance.

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Won't Fix
ComponentUE - Editor
Affects Versions4.244.25
CreatedMar 3, 2020
ResolvedJul 19, 2022
UpdatedJul 19, 2022