By Wayne Brill
Performance of out-of-process clients making multiple calls to the API will be slower than running in process like an Add-In does. One way to improve performance is to set the UserInterfaceManager.UserInteractionDisabled property to true.
Setting this property to True before a batch of changes can dramatically improve performance of out-of-process clients.
Note: Be certain to set the UserInteractionDisabled property to false after your process is complete, otherwise the Inventor user interface will remain in a disabled state.