I figured out why the sim was taking soooo long and it was because it kept going into a previous pose that I had applied before changing the pose to a different one. I had to quit out of Poser and then re-run the sim, and this time it worked beautifully and in much less time too. By the way, the Ursula Dress is now in the Freestuff area as a conforming figure. Here's a screenshot of it after running the sim: