I seem to be experiencing the same issues I have w/ Draw X4.
1. Extremely hitchy redraw performance. I've set all my settings exactly to the same specs I have in Draw X3 and it's so slow w/ redrawing after using your mouse wheel to scroll in and out or pan side to side. (reminds me of Draw 9 on the mac when you would have a stroke on a contoured object... OUCH) Although it doesn't happen w/ every file, it seems to consistant w/ files that contain tranpsarent bitmaps.
2. Thumb nails won't preview in the explorer windows, or even when opening from within Draw/Designer X4, except only in the itty-bitty tiny preview window down in the corner. It drives me crazy to open a folder full of files and not be able to pretty much instantly be able to SEE which one i want to open, with out guessing at the version, or reading each title. Seems like a strange thing to take away from the program, it was one thing that I always thought was cooler than the Adobe's.
These issues don't seem as prevalent on my Vista laptop (need to experiment more on the performance issue w/ Vista) versus a few different XP boxes I've experimented with (especially my office comp)- which each acted in the exact same manner. The thumbnails preview perfectly at least in Vista, but to me if I can't work fully in the X4's from on the go then back to my work desktop I can't work in X4 at all, and both of these issues are deal breakers for me until i get the chance to find a solution - if there is one.