In the local Rails community where I live we haven't used Heroku for a while now. Most of us have moved on to using Kamal with a VPS of our choice. The surprising benefit is that you can even host multiple rails app on a single VPS so it is ideal for playing around with multiple hosted apps.
As for raw performance I'm sure you'd get better deal with Elixir out of the box than Rails out of the box but if you wanted to keep all the benefits of Rails and scale websocket usage look into AnyCable.
As for raw performance I'm sure you'd get better deal with Elixir out of the box than Rails out of the box but if you wanted to keep all the benefits of Rails and scale websocket usage look into AnyCable.