Currently, about the best you can do is have the database on it's own server. This is what generates the most overhead, as the scripts themselves are pretty lean.
What we should probably do for 7.3, is put in an option for a master / slave database configuration. That would probably be the biggest boost. Basically, a flag where anything that updates the database would connect to the master, but anything that just needs to read would connect to the slave.
What exactly is the hardware your considering adding at this point?