The algorithm to calculate face corner normals had a vertex normal
input, with the intention to pre-populate corner normals for vertices
with no sharp connected edges. However corner normals are calculated
separately for these fully sharp vertices later anyway, so this whole
step was completely redundant. Removing the vertex normals calculation
reduces memory usage and improves performance. In a test file with a
character with custom normals, this changed improved the playback FPS
by 15%, from 41 to 47 FPS. The impact will usually be lower than that
but it should be noticeable in other scenes too.
Pull Request: https://projects.blender.org/blender/blender/pulls/133884
59f9e93413