Sapling is a Git client, so it can use Git on-disk structures, if you ask it to. But its native backend, a central server system called Mononoke, is completely

Sapling is a Git client, so it can use Git on-disk structures, if you ask it to. But its native backend, a central server system called Mononoke, is completely different in design and scope, and is in fact designed to handle very large repositories with working sets and data sizes way beyond what Git can handle. It's all a bit of a weird conversation because if you talk to an OSS programmer, a 5GB repository is "ginormous", and if you talk to some SV tech person working at corporate, they think a 300GiB repository (Windows monorepo) is reasonably large, and if you talk to a gamedev from a one off random studio, they think 2TiB is "pretty average." So you really need to be specific about the workload you're looking at.