Though some people keep trying to characterize the JFK as obsolete, there is no doubt, none at all, that if she were kept up, could do the job just as well as a nuclear powered carrier.
She can certainly go just as fast as far as I know. I doubt the nuclear power gives them more in the way of top speed, and I know for a fact the JFK could throw up a roostertail and outrun her escorts.
From an operational perspective, they just do not have to worry about refueling the vessel itself when it is nuclear.