Rails 2.3 is 9 years old this week. And it's now compatible with Ruby 2.3.
While this is not a drop-in solution and will involve some manual work for those who want to upgrade to Ruby 2.3, it will allow Rails LTS 2.3 applications to benefit from the 2x - 4x performance improvements of Ruby 2.3 over 1.8.
If you don't want to or are unable to upgrade your Ruby version, there is no action required on your part. Rails 2.3 LTS will continue to work on Ruby 1.8.7, and we are committed to supporting 1.8.7 indefinitely.
If you have already added some monkey-patches to make your Rails LTS app work with Ruby 2.x, we recommend to remove the monkey patches and follow our upgrade guide.
Some assembly required
You can now upgrade your Rails 2.3 LTS application to Ruby 2.3 without a need for the numerous patches and workarounds related to Rails that were necessary for a Ruby upgrade in the past. It also means that we will test all new releases against Ruby 2.3 (as well as 1.8.7).
However, your application will very likely have some incompatibilities outside of Rails itself (either in your own code, or in third-party gems). Upgrading will require the attention of a Ruby developer, and a moderate amount of work and testing, depending on the size of your application.
We have managed to upgrade two medium-sized Rails 2.3 applications in about 2 days of effort each. Both are now running at roughly twice their former speed. Your mileage might vary.
If you want to attempt the upgrade, we have written a detailed upgrade guide.