For small files, there shouldn't be much of a difference reading line by line or readling all the lines in a single sweep. Ruby IO handles the buffering for you. If you are really concerned about performance, why not do some benchmarking? http://www.ruby-doc.org/stdlib-1.9.2/libdoc/benchmark/rdoc/Benchmark.html -Jingjing -----Original Message----- From: NoƩ Alejandro [mailto:casanejo / gmail.com] Sent: Wednesday, November 09, 2011 9:38 AM To: ruby-talk ML Subject: Re: The fastest way to read files Sequentially... The point is that I need to process each pair of files, so I don't know which of the different ways that Ruby has to read files is the fastest. Thank you. -- Posted via http://www.ruby-forum.com/.