I suspect Python isn't the limiting factor here - it's the file format. You can end up with huge interconnected text files that have to be fully parsed on every

I suspect Python isn't the limiting factor here - it's the file format. You can end up with huge interconnected text files that have to be fully parsed on every change. If you have 1e5 - 1e6 of lines of transactions, I think a SQLite database would be a huge step forward. If you have much more than that, you probably need an ERP system. Of course the text files make it ~easy to enter transactions, but maybe there's an elegant way to use those for ingestion only; that does make the system much more complicated to use. That might not be a problem for the kind of person using plain-text accounting over the course of years though.