in reply to Performance Question
Your problem isn't in the size of the buffers Perl reads. It rarely is. But I don't understand your system setup. How can you have 70% CPU idle and load average 1.25? The only way I can see that is if you have 2 processors, and a very weird version of <samp>top</samp>.
Your numbers seem to suggest you're processing 142KByte/sec, which really isn't a lot. How fast can you copy that file on the same machine?