This node splits all faces to duplicate each time. Corner edges and vertices are just ordered sequences of indices. Most likely, due to historical reasons, this was overlooked and as a result the code became so complex with potential simplicity. The problem was found in a benchmark of #109174. The code in the lambda could not be optimized. Timings improved by about 30%, from 154 to 120 ms. Pull Request: https://projects.blender.org/blender/blender/pulls/109222