The big E has a cruiser style hull and not the fat ass variety like the Nimitz

thats one of the reasons she's so fast.
As for the rest, before gas turbine propulsion no other ship besides nuclear vessels could heat up their boilers fast enough to allow a much faster acceleration so when most of the fleet was on steam power the nuclear carriers and cruisers/frigates appeared to be hugely fast just because they always had a head start however gas turbines have negated that advantage completly.
Like I said, the
Enterprise has speed screws and the
Nimitz class has torque screws. The best way I can equate this is the V8 engine versus the straight-6. A V8 is faster off the line, but in the long run, it will be overtaken by the straight-6. If you don't believe me, then do some checking and you'll see how Jaguar, Mercedes, and others ruled the race tracks up to the mid-60's with their straight-6 engines, until Chevrolet whined that it was unfair their V8's were constantly being put to shame and had the straight-6 engines banned. The straight-6 produced torque, which always wins in the long run.
Also, the
Nimitz class (pre
USS Ronald Regan ships) are going to be retrofitted with the bulbous bow design, which adds stability in rough weather and makes the ship more efficient, and faster, in cutting through the water.
In 1989, the San Francisco Bay area was hit by an earthquake while we were on cruise (Carl Vinson). Three days later, we made our port visit to Korea, which was for two full days. The original schedule called for us to meander to Hawaii, stop for a couple of days, continue to San Diego, offload the Airwing for two days, and then head back to Alameda. The CO ordered the ship full steam to San Diego from Korea, a trip that took us three days. When the tide came in, we docked and offloaded the Airwing in a record six hours and were able to leave San Diego before the tide let out in the afternoon. The order was again given for full steam (approx 16:00 local time) and we raced up the coast of California to the Bay area, which we reach by 12:30am. We sat outside of the Bay awaiting the morning tide at 7:30am so we could dock.
Sorry, but the
Nimitz aren't slow by any means.