I've noticed that FILES is pretty slow, and I'm guessing that SB actually checks the SD card every time you call it, rather than making a list when SB starts and modifying it whenever files are saved/deleted.
A while ago, we were testing to see if there were any other banned folder names, and SB actually crashed. It seems like running FILES a lot of times (maybe with lots of different project names) will eventually cause SB to crash for some reason.