Okay, some of these problems are (unintended) direct side effects of the security fix bugs.
Like I the one about scopes that effected Github -- github quoted [this commit](https://github.com/rails/rails/commit/f980289fd2c1b9073a94b5...) as introducing the bug, which is the commit meant to address CVE-2013-1854.
So, okay, bugs happen, even with security fixes, I can forgive bugs.
But others of those performance regressions... " handing that task to Sprockets instead of resolving internally, which seems to be the cause of the performance issues."
This doesn't sound like the unanticipated side effect of a security fix. This _sounds_ like an independent change they threw into the same patch release with four (four!) security patches.
Why is Rails putting security fixes and other non-security-related enhancements together in the same patch, so you can't get the security fixes without also getting the possibly buggy new features/refactors? Does Rails actually do this by policy? Was it a mistake?
Bugs happen, including bugs in security fixes, sure. But it's BECAUSE bugs will happen that you don't throw unrelated new features or refactors into the same patch release as a security patch, so the only way to get the security patch is to risk MORE problems from the other stuff too! Come on!