Yes, this is exactly the problem. Ruby is so slow that you end up writing C extensions when you want to do any non-trivial computation. The documentation is bad, the tooling is bad, the build/CI complications are bad, and there's not much community info online about the process. And now your RoR developers have to support a C library, where a segfault can kill an entire Ruby interpreter.

I don't think most RoR apps run into these problems, which is why RoR is such a great thing in the first place, but we shouldn't brush aside how slow it is, and the implications of that when it becomes a problem.