After jailbreaking my iPad 3rd Gen, i feel that my iPad is now more snappier than before i upgraded to iOS 6.1 (previously 5.1.1). I think because during upgrade process, it kinda format all of the system and install the new firmware to the device and restore all the apps to the device again.
The same goes with most Windows installation system. When you think your system is getting slower, that might be a sympthoms to reinstall your system to be refreshed again. Doing so will clean the registry which holds most of your system and application's settings, including the one you probably have removed.
Back to the iOS case, some people reported that upgrading to iOS 6.1 will increase their battery life on iPhone 5. I don't perform any benchmark on my iPad, so i couldn't tell whether it's happening or not, but what i can tell that iOS 6.1 is causing my iDevices to be more snappier than before.