In previous versions of ArcGIS Desktop (10.3.1 and prior), BLOCK entities were grouped with the POINT layer when the DWG file was drawn or imported. These BLOCK entities are identified as "Insert" in the Entity field in the POINT attribute table. They are still included with the POINT layer, but are also separated out as individual layers from the drawing file in 10.4. This allows users to display and access attribute TAGs associated with the BLOCKs from AutoCAD.
There is, however a performance hit when the GROUP layer from the drawing or DXF file is added to ArcMap.
To avoid drawing all these individual BLOCK layers in ArcMap, just add the Annotation, Point, Polyline, Polygon and Multipatch layers to the map as was done previously. To add these specific feature types in the Add Data Dialog or in ArcCatalog, double-click the CAD file name and add only the feature types needed to the ArcMap document.
Individual BLOCK layers can also be added to ArcMap along with specific feature types. This provides access to the values in the attribute TAGs for each type of BLOCK.
Esri recommends not adding the Group Layer from a CAD file to ArcMap, because the Group Layer masks too much information about the data, and also adds all the BLOCK layers to the map, causing a performance lag. This is documented in BUG-000094769: "DWGs added to ArcMap 10.4 take several minutes to load and may eventually cause the application to stop responding."