This was on the futurebb announcement thread, but you should really use it instead of mysqli. It easily adapts to any database system, and uses a lot less resources, ultimately speeding up how much time it takes for the page to load. Its extremely useful and I highly recommend using it.

FutureBB has already been extensively programmed, and uses MySQL queries. While PDO would be nice, we are unable to restructure over 500 different SQL queries, of which many are extremely complicated and have a large amount of JOINs. If we optimize the SQL queries (which we do), the software will perform suitably.

Jacob G.
Executive director and co-head developer