Gosh, I don't know how long it would take to load ... depends on how many sounds there are, I suppose. Besides, sound files are not web pages, and opening them in pop-ups will just ask the client if they want to download. :(
If you were talking about embedding them on the pop-up, I'm not sure that wouldn't take longer to load than importing with the Flash movie.
I'd run some tests and see exactly how long the different techniques take, if I were you.
HTH,
Snib
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