Ultima VII *always* ran poorly. It's the nature of its engine. Same with Ultima VIII. The Exult remake was an engine remake which is why it's not identical to the original. DOSBox simply emulates the original game which includes the rather odd behaviour of the game.
Sound skipping is due to an improperly set-up DOSBox though. I believe 10.000 cycles was about the optimal setting for Ultima VII.
Still, I went for Exult as well. You got the big bonus of seeing a lot more of the area around you which I find very handy and of course, the improved interface which was taken from the second part.
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