Thanks for the help everybody...
Last night I tried out .36 final and .53, and the both run MUCH better with my setup. But now, of course, there's another problem: the older versions don't seem to support the autorotate parameter, which I had been using to display horizontal and vertical games correctly. I'm building a cocktail with controls on 3 sides so I can run both. I can use -norotate, but then some games point the wrong way...e.g. Galaga rotates left, but 1942 rotates right. Is there a way to get them all to go the same way in the older builds?