The page preview is quite slow as I continue to test. I'm not sure why. It gets slower the more previews I try. That's rectified (for me) but opening and closing the program.
Yes, this is a bug in Xara that's plauged me for years Bill. Eventually the xar file will just cease rendering and crash Xara. As you state the only cure is to save and close Xara. Reopening eliminates this issue for a while but it returns.

One other I've alway had is opening Utilities / Options. This take eight seconds to open the Options window!