I know this thread is old, but for anybody using EastCoast CAD CAM I hope this helps. My process for making a model to place into Navis or BIM is the following:
1. Create a layer state that includes only the duct, equipment, clearances, grills, and whatever else you have modeled in that you want in Navis.
2. Once the layer state is applied, run WBLOCK and select all items you want to include. I usually just select all and then WBLOCK. Save WBLOCK as a new file.
3. Open the WBLOCK model. PURGE all items that can be purged. Run -PURGE to purge all of the regapps.
4. I usually run overkill also just to confirm I don't have any duplicates.
5. Then the most important step in all of this is to run DUCTSCHEDULEDATA, then D for detach, then say ALL and hit enter. What takes Navis so long is loading all of the property sets as mentioned in previous replies. Running this command removes ALL of the data from the duct, allowing load times in Navis to be a fraction of the time it takes when loading a model with all of the data still attached.
6. Obviously save the drawing, I usually rill run AUDIT before saving but it isn't always necessary. I just want my drawings to be as clean as possible.
Also copy times from one drawing to another is reduced when you detach the data and once it has been copied into the drawing ATTACH of the data once again. This will attach all of the property sets that correspond to each piece.
I know that this method is effective, since I am usually working with very large jobs. I can place a 90MB model with only duct into navis and it loads in about 60 seconds. Also, the amount of RAM and CPU clock speed will effect performance, but it will still load within a decent time if you detach all the duct data.
