Stickler, thank you.
I'm pretty sure the performance issues I was having related to the grids I was fooling around with. It seems like CC either does the fill quickly or bangs its head against the wall for what might be a very long time.
At this point, I've solved thousands of puzzles but am just getting started trying to construct. I've been using autofill a lot, just looking at the results. Informative, in a way. If you just let it rip on a blank grid, in my observation you can expect a few clinkers (urine), maybe some unacceptable dupes (reopen and opens, e.g.), and a very boring puzzle, not worth any effort at cluing. Maybe if you were willing to look at hundreds of autofilled grids, you might find one decent one, but that doesn't seem like any fun at all, and it would of course be themeless. From what I gather, themeless puzzles are a rather small percentage of what gets published.