Marcel contributed a targeted performance enhancement to the metatensor/metatrain repository by optimizing the _compute_single_neighbor_list function, which is central to neighbor list generation in scientific computing workflows. By eliminating redundant calculations within this function, Marcel reduced CPU usage and improved processing speed for large-scale data processing tasks. The work leveraged Python and focused on algorithm optimization, demonstrating a clear understanding of computational efficiency in scientific applications. This feature, co-authored and committed for traceability, addressed a specific bottleneck in the codebase. While no major bugs were fixed during this period, the depth of the optimization reflects careful engineering and domain expertise.