Thank you superdoc, just a few comments regarding your answers

1) It'll be not possible for me to provide a single template as the messages are dynamic. And so require different handling dependent on what is specified.
2) I can't read an entire file unfortunately since these files can be gigabytes large and also I'll be reading from a pipe.
3) Yes - I done some further research on this and it seems perl just points to the string rather than copying it into memory. So pass by reference actually takes longer. I also don't believe that I chopped it at all, I just increased a counter.

I'll try and see if I can make a dynamic template to reduce the number of calls and take a look at these other threads to see what I can do to remove unnecessary logic.

Will provide an update...