"make better use of the computer's resources" is a pretty meaningless phrase - does it mean make the process as inefficient as possible so more computer resources are used? If it means "make this process execute in minimum time", then don't worry about it, even if the configuration file is megabytes big the time to slurp the file and process it (you did realise that the foreach slurps the file?) the time to process it is likely to be negligable. The time wasted diagnosing and fixing input errors due to a complete lack of validation on the other hand could cost a heap of time better spent drinking beer.

Get someone else to do the work for you - use a module, then take the rest of the afternoon off for a beer.