Your question is a little hard to answer, "unlimited" is hard to define. Any real database including mySQL, Oracle, Microsoft Server can hold a lot of data, yet are limited by disk size.
Being able to handle large numbers is only part of the battle, load time and seek time are also problems.
You should indicate how many individuals, families, sources, images you have in your current DB and how much you anticipate growth in the near future. This may help someone tell you about how FTM2012 and other software works with their data.
Database sizing and application thru-put all depend on these things, as well as "real" memory size and the size of the "swap file" for your computer.