We have ECW files with a NAD83 (2011) definition in the header. The header actually stores the EPSG code in this case. These files attach extremely slow with raster manager compared to a straight NAD83 header definition file. The design file we attach to also has the NAD83 (2011) coordinate system set, so it shouldn't be a reprojection issue. We are using the latest Connect update 14
.8032.test.dgntest nad83.ziptest nad83(2011).zip
Can you provide a zipped copy of the text file produced with the file already open then keying in: "show configuration"? This may provide some more (necessary) details needed to help in reproducing or troubleshooting the issue.