From Scale List Cleanup Utility README.txt:
Description of Problem
When a file contains excess scales, performance may be negatively affected. Eventually, the file may become unusable. To use the file, some scales must be removed. This utility repairs affected files by removing excess scales.
NOTE: Nested external references (xrefs) may produce excess scales. To correct this problem, install AutoCAD 2008 Service Pack 1 or corresponding service packs for AutoCAD-based products. The Scale List Cleanup Utility repairs files affected before the necessary service pack was installed.
AutoCAD® 2008-based products, including DWG TrueViewTM 2008
AutoCAD 2009-based products, including DWG TrueView 2009
Not every scale containing “XREF” in its name is a bug. Legitimate” XREF scales:
- When units are different
- When proxy objects are present
- When these scales are already used in page setups, viewports or anywhere else where scale is used.
- When scale list in XREF contains scales or definitions which are not present in the parent file
How to clean:
- Use Scale Cleanup Utility (download from Autodesk website)
- Alternatively, add the following line (before Qsave line) to any of the cleanup scripts you run on your files:
-SCALELISTEDIT R Y E