This PR does successfully remove the calls to reduceLanes from the inside of the loop iterating over the subspaces the Euclidean case. I do have a concern about applying this pattern to one specific case but leaving the handling of other cases as is, leaving the code with 2 different implementations for the same problem. Some questions:

1. Why is the optimization only implemented for the Euclidean case? In PanamaVectorUtilSupport, where the call to reduceLanes is made from the squareDistance methods which are called in a loop for the subspace count, likewise reduceLanes is called from the dotProduct methods. Why only fix one?

2. Why is the optimization only applied to diversityFunctionFor(...) and not scoreFunctionFor(...) which uses the same pattern of calling squareL2Distance(...) inside of a loop for each subspace?

@MarkWolters, thank you very much for the feedback. I can make the changes to dotProduct methods and to function calls in scoreFunctionFor()

@shyla226 please be aware that in order to pass the automated GitHub action regression test any pull request must come from a branch inside the datastax/jvector repository and not a fork of the repository. So while I am willing to review the PR from a fork and provide commentary, in order for it to pass the requirements for merging it will have to be a branch and not a fork.

@MarkWolters, Sounds good! I will create a branch

@shyla226 I don't think you'll have sufficient permissions to push a new branch to the repository. For now you can keep the changes on a fork and they can be reviewed there while we come up with a solution to this issue.

@MarkWolters , I have added new functions to include dotproduct & cosine for diversityFunction.
I have also added overloaded function for scoreFunction, for all the 3 cases

Thanks @shyla226, I will review the updated code asap

Thank you very much @MarkWolters . With the changes, when M=64, dot product shows ~30% reduction in latency & COSINE shows ~43% reduction

@MarkWolters sorry, accidentally closed it! I will update the test setup used in the description above.

@MarkWolters, I have addressed the issue with the 2 failed checks and tested the code changes on Windows server

@shyla226 apologies for not addressing this sooner. I have created a branch named reduce_lanes based off of the latest main. Please rebase your change on current main and open a pull request from your fork to the reduce_lanes branch. From the Github UI you should be able to select Contribute --> Open Pull Request and in the resulting screen select the branch you wish to merge to. From there we can run the internal github actions and regression tests and get your changes merged.

@MarkWolters Thank you very much. I will rebase the changes.