It seems like you misunderstand my comment. The idea I'm getting at is that it's usually something else besides the programming that is the bottleneck, not that bottlenecks don't exist. You're going to hit architectural and database issues long before you hit Ruby's GC in most applications.
I understand your comment, and I disagree with it. Most specifically, I disagree with the "long before" part of it. In my experience, code performance has been roughly as important as architectural and database issues. You will have to deal with all of them, and on roughly the same time scale.
