U mean scroling inside cydia or scroling generaly also in apps n setings etc? Mine works as always! Also jbken my iphone4 today n no prob. Mayb u should rejailbreak?
It's not slower at all. However, not all applications are able to scroll as smoothly as Apple's own (ie Safari) due to the fact that they haven't got access to the same APIs. That's why apps like iCab Mobile Browser scrolls jittery, whereas Safari scrolls smoothly. It's supposed to be "fixed" in iOS 5.