When opening or modifying drawings containing a lot of geometry, AutoCAD Architecture and MEP toolsets can become slow or unresponsive. This is because AutoCAD Architecture and MEP toolsets are drawing or in the case of modifying or copying, re-drawing all the geometry in the drawing.
To improve the application responsiveness, set SETENABLEPROGRESSIVEUPDATE to Yes. This ensures that only graphical representations of geometry is drawn at the first instance and that the entire geometry is drawn when AutoCAD Architecture and MEP toolsets are in the quiescent or idle state.