If your drawing contains a lot of 3D solids, this issue is probably related to the new features that require more resources to process 3D solids.
To speed up the loading process, you can turn off the Solid History of the 3D solids. Follow these steps:
- Select all of the 3D solids in your drawing.
- Right-click. Click Properties.
- Select None from the Solid History drop-down list.
- Save your drawing.
The next time that you open this drawing in AutoCAD® 2007, it should load quickly.
Note: The SOLIDHIST variable controls the default History property setting for new objects. If SOLIDHIST is set to 1, composite solids retain a history of the original objects contained in the composite. If SOLIDHIST is set to 0 (None), no history is retained.