Vault modification

We've added some throttling code to help keep vaults from generating lag in certain situations. (These weren't common situations, but when they popped up it was a real problem.) I won't go into detail about the changes themselves (no sense feeding the dupe monkeys), but if you notice anything odd about vaults please report it to us.

Many thanks to Fireblade for working with me on this and figuring up an elegant code solution.