This is a packaged version of CSVScan, written by MoonWolf. If you can read Japanese, checkout README.ja for whatever he said. On a 10,000 line file: time cat example.csv | ruby fastercsv_benchmark.rb real 0m8.804s user 0m8.502s sys 0m0.304s time cat example.csv | ruby csvscan_benchmark.rb real 0m0.860s user 0m0.782s sys 0m0.088s