You can convert AutoCAD Civil 3D stock subassemblies that are VBA-based to .NET. In AutoCAD Civil 3D 2007, and in earlier versions of AutoCAD Civil 3D, the subassemblies that were included in the product were created using VBA.
In AutoCAD Civil 3D 2008, all of the subassemblies included in the product were created using .NET. This is because .NET versions of subassemblies provide faster performance than VBA-based subassemblies when generating corridor models. AutoCAD Civil 3D 2008, and later versions, still support VBA-based subassemblies. For example, in drawings, catalogs, and tool palettes, you can have a mix of VBA-based and .NET-based subassemblies. However, it is recommended that you convert VBA-based subassemblies to .NET using the following procedure to achieve optimal performance when generating corridor models.
To determine if a subassembly is VBA-based, .NET-based, or created from a polyline, use the Subassembly Properties dialog box or the Properties palette to display the subassembly definition.
The Defined From field displays .NET if the subassembly was created using .NET, VBA if it was created using VBA, and Entities if the subassembly was created from a polyline.
The Geometry Generate Mode property displays .NET if the subassembly was created using .NET, VBA if it was created using VBA, and Entities if the subassembly was created from a polyline.