Now here's a funny fing to file under the 'funniest things since mad Mick McMad won the Maddest Man competition' folder. After much pondering about what goes on in my VM when Morphic is in action, I found that changing the platform code attached to ioForceDisplayUpdate to do nothing made Morphic run 3-5 times faster. It's amazing - I know have snappy response menus, typing goes smoothly, drag-selecting is fine, all that stuff. So far I can only surmise that something about the prim implementation/usage was massively overpowering the graphics system. Right now though I'm just enjoying the new pleasures of a usable UI :-)
tim