 <p>Recently (only a few months ago) the folks behind <a href="https://www.phusionpassenger.com/">Phusion Passenger</a> add support to Heroku. Definitely this is an alternative you should try and see if fits your needs.</p> <p>Is blazing fast even with 1 dyno and the drop in response time is palpable. A simple <a href="https://github.com/phusion/passenger-ruby-heroku-demo">Passenger Ruby Heroku Demo</a> is hosted on github.</p> <p>The main benefits that Passengers on Heroku claims are: </p> <ul> <li><p><strong>Static asset acceleration through Nginx</strong> - Don't let your Ruby app serve static assets, let Nginx do it for you and offload your app for the really important tasks. Nginx will do a much better job.</p></li> <li><p><strong>Multiple worker processes</strong> - Instead of running only one worker on a dyno, Phusion Passenger runs multiple worker on a single dyno, thus utilizing its resources to its fullest and giving you more bang for the buck. This approach is similar to Unicorn's. But unlike Unicorn, Phusion Passenger dynamically scales the number of worker processes based on current traffic, thus freeing up resources when they're not necessary.</p></li> <li><p><strong>Memory optimizations</strong> - Phusion Passenger uses less memory than Thin and Unicorn. It also supports copy-on-write virtual memory in combination with code preloading, thus making your app use even less memory when run on Ruby 2.0.</p></li> <li><p><strong>Request/response buffering</strong> - The included Nginx buffers requests and responses, thus protecting your app against slow clients (e.g. mobile devices on mobile networks) and improving performance.</p></li> <li><p><strong>Out-of-band garbage collection</strong> - Ruby's garbage collector is slow, but why bother your visitors with long response times? Fix this by running garbage collection outside of the normal request-response cycle! This concept, first introduced by Unicorn, has been improved upon: Phusion Passenger ensures that only one request at the same time is running out-of-band garbage collection, thus eliminating all the problems Unicorn's out-of-band garbage collection has.</p></li> <li><p><strong>JRuby support</strong> - Unicorn's a better choice than Thin, but it doesn't support JRuby. Phusion Passenger does.</p></li> </ul> <p>Hope this helps. </p>