Frozen string literals are supposed to speedup the code. But majority of Ruby and Rails code needs patching to support this feature. And it turns out it’s easy to make performance worse in the process. Learn how to avoid making this mistake: http://ruby-performance-book.com/blog/2016/02/is-ruby-2-3-faster-how-to-prepare-yourself-for-frozen-string-literals-and-not-lose-performance.html