I don't code so idk the deep dive but from what I've seen from the people who run my instance, there's a lot of features missing and sometimes updates break things.

Last I checked, Piefed, despite being written in a scripting language, manages to be much faster and lighter.

I can't comment too much on database best practices, but apparently the way Lemmy uses them is borderline insane. It does just visually look pretty speghetti-code-ish, in those sections. Hopefully, one day somebody will come along and fix that.

The rest seems fine.