When using the Python window in Pro, or ArcMap for that matter, you are often working with the layers that are loaded in the map. When you use a command such as arcpy.SearchCursor() Pro will query the map and present a window with a list of layers that are loaded into the map. When you have many layers, or even a few it seems, it takes forever for it to generate the list. Could this be improved upon? One would think this data would be cached somewhere but it seems Pro refreshes itself in many places that actually make it feel slower than ArcMap. At least while it is generating this list it does not freeze the application like it did in ArcMap.
Also it seems that you can no longer drag layers from the Contents pane directly into the Python window. Please bring this functionality back.