Puma works great on Heroku. Rubinius, on the other hand, doesn't. It was incredibly slow, the app took more than a minute to boot up which caused Heroku to thin

Puma works great on Heroku. Rubinius, on the other hand, doesn't. It was incredibly slow, the app took more than a minute to boot up which caused Heroku to think it crashed. However, you can still use Puma with MRI 1.9.3 or something else and it'll still work great.