Thanks for your reply - I had thought about limiting the split, but I didn't believe it would enhance performance much. It does appear to help though. The simple reduced split you noted seems to improve performance by about 20%.
However, the other snippets you provided don't work. I'm trying to figure out why. They return no matches for files I know exist.
Odd. Admitted, I didn't test them except for the regex in the last snippet when I posted them, but I did now and they seem to be working. *shrug* There's nothing obvious I can spot either.