Look at the size of the files for the Haiku OS image — it sure is small, and it can still perform well. As of late there is no graphics acceleration and it only launches on an emulator, but even inside qemu on my Mac it boots to a usable desktop almost instantly.

1 — The build folder: haiku-minimum.image is the whole operating system.

2 — Haiku under qemu on macOS — desktop and Tracker up in seconds.

A lot of huge, fast progress has been made toward the release of this operating system, and it looks promising. I think I am going to dive in and start contributing to this cause.