DWG files increase in file size and file performance degrades in AutoCAD

 Issue:

Drawing files in AutoCAD end up being much larger than they should, often with no obvious data in them. Other symptoms include:

• Failure to copy and paste elements.
• Hanging for a long time when selecting text with the properties palette open.
• Drawing file takes a long time to open.

Causes:

• Corrupt data in the drawing.
• The DWG was created in a non-AutoCAD application.
• A large amount of AEC objects or metadata in the file. 
• Data is imported from a DGN file and the original linetypes were not mapped or were incorrectly mapped to AutoCAD linetypes. This produces a huge object database in the drawing that cannot be purged with the standard tools. Furthermore, when copying and pasting an entity from an affected drawing into another, the entire database is copied along with it. The problem spreads to the other file.

Solution:

Try one or more of the following:

File repair and maintenance

• Repair corrupt drawings (see How to repair corrupt AutoCAD files).
• Optimize the drawing:
  • Optimizing the AutoCAD drawing file: Wblock Purge.
  • Optimizing the AutoCAD drawing file: Windows Clipboard Copy and Paste.
  • Optimizing the AutoCAD drawing file: Purge, Audit & Recover. Check the box for "Automatically purge orphaned data" when purging.
• Convert AEC objects and clear out metadata in the file (see EXPORTTOAUTOCAD (Command)). 
• Reduce the number of Viewbase Drawing views in any one layout, or attach the views as an external reference (see About Attaching and Detaching Referenced Drawings (Xref)s).
• Export then reimport the file using:
  • The DFXOUT and DFXIN commands. 
  • The DGNEXPORT (select V8 DGN format) and DGNIMPORT.
• Clean DGN linetypes from the drawing (see How to clean DWG files from the extra DGN linetypes with AutoCAD 2015 or greater).

Update applications

• Install the latest AutoCAD updates (see Install updates, add-ons, and enhancements).
• Uninstall older versions of DWG TrueView and install the version matching the currently installed AutoCAD release