SQLite is totally capable of delivering a good performance. The main problem is that you have to take care of efficiently opening and closing the file yourself.

SQLite is totally capable of delivering a good performance. The main problem is that you have to take care of efficiently opening and closing the file yourself. Naively doing it for every user/transaction will quickly put an end to your scalability plans and in fact, it is something you get with a DB server applications for free. That said, it's strength is its simplicity and not its scalability. So if you plan to run a database server cluster, you probably want to look for other technologies. But as long as you are on a single machine, your SQLite performance problems are probably a case of 'you are doing it wrong' ;-) So when you are talking about server-side, you probably don't want to limit your technology choice to a database engine that can not be clustered. However, if you are offering software which should be simple to install on a server (e.g. Nextcloud), providing an SQLite option is probably a good idea, because nobody has to care about DB-Server administration and connection setup.