The first thing you should do before bothering the devs is make sure that it is in fact the drivers that have regressed. And is not caused by something else to do with other updates in Fedora 19. Building and running mesa 9.1 should help determine this.
I have a quick guide to building the intel drivers as part of my (incomplete) Introduction to Mesa: http://www.itsqueeze.com/2013/09/int...rough-example/
You will need to checkout and build the 9.1 branch from git.
If the performance is better in 9.1 you will then need to do a git bisect. Quick google explanation: http://webchick.net/node/99 basically you will need to use it to build different commits of mesa between version 9.1 and 9.2 until you find the problem commit.
Then once you find the problem commit you should report a bug following the procedure here: http://mesa3d.org/bugs.html