Author: Matt Miyamoto AutoCAD

The Ideate tech team has seen a recent increase in cases related to poor performance, slow opening and saving of files, and a number of crashes when using basic AutoCAD commands.  When these types of issues occur, one of the first things we look at is file size (is the file larger than expected) and file cleanup tools.

Two of the most common contributors to abnormal file size and poor drawing performance are Scale Lists, and RegApps. When the number of these items in a file increases, so does the file size, which hinders drawing performance.

The AutoCAD Scale List is a list of pre-defined drawing and annotation scales that are saved in a drawing file. Scales can easily be selected from the list to automatically resize any annotative content, like lineweights and annotative text, dimensions, and multi-leaders. Scale Lists can also be used to quickly set a scale for viewports created in a layout tab. In order for a scale to be selected, it must be defined and included on the list. Scale lists are also updated to include scales from external reference (XREF) files and other objects that contain scales that were not previously defined in the drawing’s original Scale List. This can add tens or even 100+ scales to an existing drawing, many of which aren’t necessary for final plan sets. Scale Lists should be cleaned of excess scale values when possible.

In the case of RegApps, according to Autodesk, RegApp is short for “registered application." It is linked to “extended entity data” (XDATA) that is attached to drawing objects through use of Autodesk’s provided APIs. Unreferenced RegApps appear in a drawing when the original objects that contained XDATA are deleted from the file.  Because the RegApp remains after the object has been deleted, it’s an extra bit of data that contributes to larger file sizes and negatively impacts performance of a drawing. Unregistered RegApps need to be purged from a file in order to remove them from the drawing’s database.

Scale Lists and RegApps can be manually removed from individual drawings using a couple of drawing cleanup commands, but there are some misunderstandings that we’ve run into in the past as well.

The SCALELISTEDIT command can be used to access the Edit Drawing Scales dialog box. From the dialog box, you can delete existing scales from the drawing, or use the Reset option to reset the scale list to the default values. Although they are similar, the results of the two options are quite different. If you select all scales in the drawing (you can use shift+left click to select multiple items) and use the Delete option, only scales that are not in use will be deleted. Any scales that are currently referenced in the drawing will remain on the list. If you chose the Reset option instead of delete, you will be prompted to select a default scale list (imperial, metric or both). In this case, the existing scale list will be replaced by the default option selected. Any custom scales added to the list will disappear, along with any unreferenced scales. You may also end up adding additional unreferenced scales since it is importing a full list of defaults rather than just what’s being used in the drawing. In any cases, both options should help with issues related to excessive scales, but the Delete option does appear to reduce the number of scales in the file more than the Reset option.

RegApps must be purged from a drawing, but they are not found in the standard PURGE command. In order to access the RegApps option, the –PURGE command must be used. Adding the “-“ symbol to the front of an Autocad command like PURGE will give you access to the root options built into that command. The list of additional purge options will appear and allow you to select these added features along with the standard objects that the PURGE command allows.



One of the biggest misunderstandings with this –PURGE list is the “ALL” option located at the bottom. Although it says ALL, that option does not include everything in the list. The PURGE command is also limited to removing one level of reference at a time, requiring multiple uses of the PURGE command in some cases before all unused data has been removed. For RegApps, Zero-Length Geometry and Orphaned Data, these items must be selected individually for removal and are not part of the “All” option. The Purge command also does not remove unnamed objects from blocks and locked layers, so some of these may remain in the file after the process is complete.

The two commands mentioned above (ScaleListEdit and –PURGE) are individual drawing based commands. In order to help with the cleanup process of multiple files, Autodesk has created two utilities that can be downloaded and added to your Autocad installations. Both utilities are setup for multiple files (batch processing) and work in a dialog box external to the Autocad application, eliminating the requirement for each file to be opened and cleaned manually.

The RegApp ID Cleanup Utility can be found here (for versions 2008-2016).

The ScaleList Cleanup Utility can be found here (for versions 2008-2016).

The links also include instructions on how to install the utilities and how to run them after installed. The files need to be copied to the Autocad installation folder for the version you are installing, which is typically found at: C:\Program Files\Autodesk\AutoCAD <version>

The CleanupRegapp.exe will launch a dialog box that looks like this:



From here, you can load files or select entire folders for removal of RegApps in one bulk process. This is extremely useful in the case of XREF files, where RegApps in an XREF may carry over back to the base file even after that file has been purged.

The CleanupScales.exe file launches this dialog:



From here, you can select files or folders and choose to remove unreferenced scales down to a user defined max value and select a reference template for populating the new scale list similar to the Reset option.

On a recent support case, using these utilities on a set of 18 drawings in a project folder removed over 200,000 RegApps and 500+ Scales from the scale list, and some drawing files were reduced to 50% of their original size, which significantly improved performance in Autocad.

Next time you’re running into issues with poor performance or long lag times and freezes when working with basic commands, remember these two utilities and see if they are able to fix the problem. And for more information on drawing housekeeping tools in AutoCAD, check out this post, AutoCAD Drawing Housekeeping, from fellow ENI Tech Daniel Armstrong.

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For more information on the software solutions, training and consulting Ideate provides, please visit the Ideate, Inc. homepage.

     Matt Miyamoto
Matt Miyamoto
ENI Manager & Senior Application Specialist

Matt is an ENI Manager and Senior Application Specialist in Ideate, Inc.’s Seattle office. He has a B.S. in Mechanical Engineering and is a licensed Civil Engineer. Prior to joining Ideate, Matt worked as a civil engineer, using Civil 3D on a variety of projects including site development, roadway improvements and infrastructure design. With over 10 years of experience in the civil engineering industry, Matt now provides training, consulting, technical support, and implementation strategies for organizations transitioning to Civil 3D. Matt is an Autodesk Certified Instructor (ACI), as well as an Autodesk Certified BIM Specialist: Roads and Highway Solutions. Additionally, Matt is and Autodesk Certified Professional for AutoCAD, and AutoCAD Civil 3D. You can also find Matt on Twitter.