CSV::Table#to_csv should use concat not +
ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-linux-gnu]
The current implementation of CSV::Table#to_a method uses Array#+ to which is really bad on performance. It seems like it should use Array#concat.
Relevant Github PR: https://github.com/ruby/ruby/pull/946