It is nearly impossible to guess what will or will not make a Perl program faster. The usual advice is to profile your program. Only work on those parts which are using the most time. Use benchmark to measure possible improvement. In your case, I/O is probably taking much longer than processing. Slurping the entire file into memory is probably not an option. Reading the file in large blocks may help, but it is not easy to get right. I recommend against any optimization unless it is absolutely necessary.

I noticed something interesting about this document: If I view it with the 'more' filter. I see a bunch of black rectangles with the tags inside them. If I view it with gedi or ptked I see \x{93} , \x{94} , \x{95} , etc. Does it matter what chars go in my s/ ... / line? What does PERL see?

Could you post a representative sample of your input file, following the advice given here and here?

what makes you think it's not fast enough?

Update

quoting davido from the CB:

who cares about how fast Perl runs; it's almost always the network or IO that are standing in the way.