Wasted about a day trying to troubleshoot DWGs Xrefs (each some ~40,000 elements —large, but not huge) in AC 22 —repositioning them took 25+ minutes, bringing in both objects and lines, simplifying fills or not, teamwork or local, worksheet or story, SPA and USA. We then tried AC 21, same problem, and then AC 20 and everything went smooth (again, in all variations). This has been painful. Anybody understands what the problem may be? Wouldn't want to move the project to 20 because of this.
