Carbonite is now being updated on
Curse.com.
As for the FPS issue, make sure that the Blizzard "Zone" (the one you open with "shift + M") map is closed. That used to be an issue for some people's set up, but I thought that was fixed back in Cataclysm. I don't personally use that map so I have never had the issue.
If that map isn't open, make absolutely sure that
ALL of your addons are up to date, and make sure you either have "Display Lua Errors" turned on in Blizzard's "Interface > Help" options, or you're using an addon that catches Lua errors.
!BugGrabber and its' partner
BugSack are excellent for that. The reason for this is because if you have no way to show/catch/see the Lua errors, you might be getting a lot of them and that has been known to effect frame rates. It might not be something that will break your game/UI, or something like that, but it's enough to cause your game to slow down.