1. if you're writing a daemon, or somesuch, then excessive screen output will slow it down tremendously. But in the world of CGI scripts, that's not a real issue. And anyway, it's not the print *function* which is slow, it's screen output in general.

2. I would have thought that $_[0] would be marginally faster but again, for CGI purposes, it's not a real issue. Don't sweat the small stuff.

3. Yes, it'll slow the compile down a bit. But I think it's worthwhile having, because of the work it saves you. Do you *really* want to write your own cookie-parsing routine??

As someone else has already stated, I doubt strongly that any of these are actual problems for you if you're working in a CGI environment. Look elsewhere.. are you using a db, for instance? Having file-locking issues? Profile your code, see what gets run the most and streamline those bits.