Hey tabby, was doing some testing on HTHvT0672 and found that running it using Ruffle emulator allows the game to use full GPU acceleration. With this implemented all of the areas load fast and smooth, and animations play at the correct speed. One major caveat is noticeably slower load times. The emulator has versions for Linux Mac and Windows, and you could create batch/run files for each version.
EDIT: I forgot to mention that the reason we shouldn't add this for a while is that it doesn't seem to load external .swfs so character scenes can't be loaded from the game. If this is rectified this emulator might be the next best step for this game.