As your batteries get weaker, the flash recycle time gets longer in between shots. I recommend that you bring a few extra sets of rechargable batteries, charge all of them the night before you leave to WDW, and charge all of them at the end of each day while you're at WDW. When you notice the flash recycle time getting unbearably long, pop a fresh set of batteries in the camera. I've heard on this board that you can leave your batteries & charger at select WDW park locations, and the CMs will plug it in behind the counter to recharge.
There are little things you can do to prevent the batteries from wearing down prematurely. Turn off the camera when you're not using it. Avoid using the LCD screen to review and delete picture (wait until you're done taking pictures for the day to review and delete pictures, then recharge the batteries). If your camera emits a light intended to reduce red-eye, turn it off (it doesn't really help). Turn the flash off if the subject is farther away than 10 - 15 feet (refer to your manual to determine the effective range of your camera's built-in flash). Be judicious with the shots you take.