Hi peachsb...
The delay you're seeing may be due to some network or disk latency.. and inserting a Pipe/Duct is an inherently more complex operation... vs Copying an object that already exists, or drawing a Line which is not dependent on external content files.
In a 'new' drawing, when you use these commands, AMEP first has to check if the Layer Key Style you have configured as default is in the drawing, if it isn't, it loads it in. Subsequently, when you use these commands, it has to reference the Pipe/Duct catalog, which, if you have a slow network connection to your content, may experience a greater than normal delay vs. if the content is local.
As you are modelling in AutoCAD MEP, if the object style already exists in the drawing, (i.e., such as a 6" commercial pipe) it won't need to access the catalog... however, if you are routing pipe, and are constantly inserting unique objects, there will be a slight lag for it to load the content from the catalog... it shouldn't be 10's of seconds or minutes, but a slight perceptable delay.
Now, as a caution, I have seen where customers have tried migrating forward profiles from prior releases of AutoCAD, and in some cases even MEP, which, for some reason beyond my knowledge, causes more significant delays in these types of operations.
Martin Schmid
Product Line Manager
Mechanical Detailing and Electrical Design
Architecture, Engineering, and Construction
Autodesk, Inc.