Perl is always going to be much faster than Java at tasks like this. Use stdin and chomp() instead of reading each line explicitly.

This is really a small, trivial task for a perl script. Even with a billion lines this is nothing for a modern cpu and perl.

/r/perl would beg to differ:

https://www.reddit.com/r/perl/comments/18ygpsi/1_billion_row...

Reddit?