Although this is a Perl site, when you start playing with things as a block of data, I start thinking C/C++. Perhaps you should consider that as well... For data organized in \t and \n delimiters you should be able to parse it quickly in C. Whether you can do whatever operations on that data easily in C is another question, but one I think is worth asking yourself if runtime is a serious consideration. I'd also double check for anyplace you might need an eof(). Possible corner cases that might be good tests for the chunk() code is where you have a \n as last char in file, and where you do not.