Why are you using cat at all? Use a pipe. This isn't hard stuff. Don't use <>, feed the file into a scalar or array. it should only take a few seconds to proces

Why are you using cat at all? Use a pipe. This isn't hard stuff. Don't use <>, feed the file into a scalar or array. it should only take a few seconds to process a billion lines. https://www.perl.com/pub/2003/11/21/slurp.html/#:~:text=Another%20major%20win%20for%20slurping%20over%20line%20by,Plenty%20of%20work%20for%20each%20line%20read%20in https://www.perl.com/pub/2003/11/21/slurp.html/#:~:text=Anot....