Depends on what you're doing, I guess. If you're just working with Python dictionaries with occasional background flushes to disk then it would be very fast.

Depends on what you're doing, I guess. If you're just working with Python dictionaries with occasional background flushes to disk then it would be very fast. Probably close to as fast as anything else. Of course, there's a lot more to a DBMS than just reading/writing in-memory data structures and occasionally saving them on your hard drive.