Keep an eye on your Undo Buffers!
 

Found out that Vegas likes to really be tedious in saving every single modification of a mask when your rotoscoping into the Undo Buffer. In fact, my Undo Buffer reached 629MB rotoscoping 10 frames.

If you're doing tasks involving heavy amounts of animation, keep a really close eye on your disk space, as that is the Undo Buffer getting progressively larger.