As a follow up on this:

VertexInterpolators are added to the HLSL code even if unused and you demand the HLSL compiler to strip away unused functions (not a big deal if that code compiles). Another issue I noticed is that the unused vertexinterpolator functions access some scalar/vector params and view params that are kept in the allocated buffers (even if the function is removed by the compiler).

In some of our shaders I noticed an increase in total op count just by adding an unused (and stripped) Time * Param vertex interpolator.

I attached two pixelshaders:

58_ps.txt: comes from a simple material (basecolor+normal+cavity*specular+roughnes+ao)
60_ps.txt comes from the same material to with I added an unconnected Time * Speed param VertexInterpolator

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There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-143150 in the post.

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ComponentUE - Rendering - Materials
Affects Versions5.0
Target Fix5.3
CreatedFeb 17, 2022
UpdatedFeb 1, 2023