`Smarty-pants'? If you a referring to my IQ, yes. If you are referring to my code, *meh* more like experience and a few books (In AutoLISP: it is better to operate on a list. In programming: it is always better to K.I.S.S.).
But you had to see something like that coming didn't you (I thought I taught you how to build a substitution model)? ...You were putting a heck of a lot of information on the Stack; you would have done better to use a recursive procedure with an iterative process instead. I would be willing to bet that my procedure would still have been faster but at least yours would have been able to handle a longer string then it currently does.
Anyways, I'm going to a friends house for food and a movie. Take care.