When referencing large, numerous IFC files into a dgn file in AECOsim Building Designer, the loading process and manipulation of the files become very slow. It is not as fast as it is in an ifc viewer.
AECOsim Building Designer is not a viewer so the program has to transform the existing IFC format of these files before it is opened, whereas, Solibri or even Bentley View is able to read these type formats natively. This is what take more time when viewing and manipulating in AECOsim Building Designer.There are no settings to tweak in order to make it any faster. Turning off reference settings for Snap and Locate in the reference dialog does not make any difference as long as the Display setting is on.
Also, you can further optimize the IFC files using IFC optimizer in ABD which can reduce the file sizes and make it faster to open.