OTOH thanks for the "eval" advice but in my camel book performance chapter 24 point 6 it says avoid eval on a string and in a loop. Here we're doing both. So now i really wonder who i should believe, some anonymous guy on a forum or a book written by Larry Wall . Gee, that's a tough one ...

If you've already decided to take the advice of Larry Wall, why did you bother to ask?

Also your understanding of IO is wrong : it's much more likely that the module data will already be in memory since we have a lot of files to process for each module function.

Yeah, whatever. It's always useful to not tell important details of the problem you are enquiring about, and to be bitchy if an answer you get didn't consider this detail.