SQLite is a file and thus uses file-level locking and does not have row-level locking. Data can not be read the same time anything is being written, so it is usually not great for multi-user applications or web applications.

Development, or 1-3 user web app it should perform OK. It doesn't scale and you will get db locks and retries if its under too much load.

To speed this up (if you must use SQLite), use a solid state drive as I/O performance is the biggest bottleneck.