Pre-computed similarity indexes

Hello all,

I noticed that Git LFS-tracked files cannot correctly detect renames, probably because Git is not doing a similarity check on the content. Doing so would require having the content (instead of just the LFS pointer), and that would require running the smudge filter, which could take a very long time due to network requests, very expensive if done on every file in the repo. When doing a `git log` for example, it would need to run the smudge filter on all LFS files in all revisions, potentially pulling down all the content from the LFS server, just to decide if there were any renames.

I wonder if there has been any thought given to whether a similarity index can be pre-computed somewhere? (Maybe upon commit with each of the commit's ancestors.) Or if this limitation has been discussed before here.

Thank you, Philip Peterson