in reply to maximum number of lines for negative lookahead assertion (?!)
I've run your script on an FC3 machine and it crashed at 8864; however on a Mandrake 9.0 machine running perl 5.8.0, it's still running and it reached 25000 so far. My best guess is something's going wrong with UTF-8...
update: Enough done, I killed it at 55264.