Ruby 2.2.0 在假期前釋出：「Ruby 2.2.0 Released」。
在「Notable Changes since 2.1」的部份有提到新的 GC algorithm (Incremental GC) 以及讓 Symbol 可以被 GC (Symbol GC)，而且提到了 Rails 5.0 會受益於此：
Recent developments mentioned on the Rails blog suggest that Rails 5.0 will take advantage of Incremental GC as well as Symbol GC.
在 Rails 這邊的說明：
Rails 5.0 will target Ruby 2.2+ exclusively. There are a bunch of optimizations coming in Ruby 2.2 that are going to be very nice, but most importantly for Rails, symbols are going to be garbage collected.