There is no such thing as "RPS for the framework". It depends on too many external factors. If I say 7652, what does that tell you?
It also depends on the requests. Are you requesting the "hello world" page, or testing real-life-app functionality?
FuelPHP's code is optimized for speed. It doesn't load anything more than needed, it has an autoloader that can locate classes with no or very few file system checks, and all core code is constantly under review. It provides an ORM, crud models or a native query builder for database access, so you can make a choice as to wether you want convenience or raw speed.
FuelPHP has core support for caching, and supports backends such as APC or memcached for both caching and sessions to further inprove the speed of the application.
So i'd say "FuelPHP is pretty damn quick".
My personal experience is that it's quite fast. Faster than other frameworks I've used.
And it's not only faster in execution, it also develops a lot faster (once you get some experience).