[apeacox]

Even if you can potentially run several instances per server (with enough ram), I think that an usable one should run on a dedicated server. Considering that a Rails app doesn't run like a webserver with php installed, just like you can do with WordPress or php apps in general. Also, I suppose 1gb is required to run the instance, but it isn't known how many users can host decently.

[hugogameiro]

I think I understand what you are saying but depending on the use case it is not only usable but it runs great.

I have instances with a couple of thousands of users and it runs smoothly with shared resources.

It really depends on what you want to build. If you want to create an instance for a small specific group of people or you want to open it to the masses. I haven't tested concurrent users but I can tell you from all the instances I run, nobody ever mentioned an issue of slowing down when experiencing heavy traffic.

I have noticed that cPanel has been pushing RoR https://documentation.cpanel.net/display/ALD/Ruby+on+Rails and I haven't tested it or know of the security implications but I am pretty sure that with enough tweaking one could install Mastodon on a cPanel server with other apps running in PHP.