As a workaround, there is a compiled DLL file which purges DGN linetypes.
Do the following:
- Download the DLL and unzip the file.
- Right click on DgnLsPurge.DLL and ensure that it is not blocked.
- Launch the Netload command and load DgnLsPurge.dll.
- Run the DGNPURGE command.
BricsCAD takes a longer time than AutoCAD to handle/save drawings which contain DGN linetypes which also unnecessary increase drawing size.
The cause cannot easily be removed. There can be a lot of these linetypes due to previous bugs in AutoCAD which caused cumulation of these linetypes. The recommended approach would be to purge the linetypes, only PURGE does not apply to custom entities such as DGN linetypes.
The sources for the DLL are listed here.