I haven't seen this one suggested anywhere and it's the one that finally worked for me, so I figured I'd share it for posterity. Open dosbox_redguard.conf in the installation directory. Find the line "cycles=max" and change it to "cycles=51000" (without the quotation marks). It's not perfect, it requires tweaking in-game using cycle up and cycle down (ctrl+f11 and ctrl+12), but it is miles better than how the game comes from GOG. The magic number seems to be somewhere in the range between 50000 and 80000; this might depend on your PC as mine isn't very powerful. For me, as the cycles approach 80000, the framerate gets smoother but the audio stutters more and more, especially during combat and dialogue.
