I just upgraded to Catalina and Dorico became more stable. I was getting constant crashes before. The problem was a MOTU MIDI device driver. It was a little cranky, and whereas Logic would complain about it (e.g. after sleep, saying the interface disappeared), Dorico would crash or hang. With the OS upgrade I was able to update the driver to a newer version and now all is well.
So if this means anything Dorico is just more sensitive to drivers than other DAW’s. So carefully curating your audio drivers and upgrading them might be in order. I’d also run diagnostics on your computer, if not do a reinstall of the OS. In this case I think it could well make a difference.