The Mythical IO-Bound Rails App | byroot’s blog

I want to write a post about Pitchfork, explaining where it comes from, why it is like it is, and how I see its future. But before I can get to that, I think I need to explain a few things. When the topic of Rails performance comes up, it is commonplace to hear that the database is the bottleneck, so Rails applications are IO-bound anyway, hence Ruby performance doesn’t matter that much, and all you need is a healthy dose of concurrency to make your service scale. But how true is this in general?.