@rootnode snac2 is minimal and small. It’s well engineered and light. littleFedi is in go and the binary is larger, bringing with it more dependencies, but still trying to be as lightweight and minimal as possible, while supporting all the possible features (like local timelines, bubbles, blog generation, etc). It supports SQLite and, for larger instances, PostgreSQL and the possibility to run more instances on the same DB, to make it more scalable.