ArcMap uses more CPU when editing maps with larger numbers of layers. This is most noticeable when running multiple instances of ArcMap on the same machine, for example, in a Citrix or other multi-session environment.
In an edit session, the following tools on the editor toolbar are enabled according to the contents of the map:
• Edit Annotation Tool
• Reshape Features Tool
• Cut Polygons Tool
• Split Lines Tool
• Rotate Tool
The enabled checks on these tools can use a large percentage of the CPU when there are many layers in the map and many instances of ArcMap running.
Solution or Workaround
The enabled check on editor tools can be suspended by setting a registry key for each user. Suspending these checks causes the tools to be enabled all the time regardless of the contents in the map. For example, the Split Line tool would be enabled even if there are no line layers in the map.
To suspend the enabled checks on editor tools, add the following registry key for each user.
DelayCostlyEnabledChecks dword = 1
This solution has also been implemented in the ArcGIS 10.2.1 Utilities and Telecom patch. The same registry key can be used with a 10.2 path.