You need to run CADWorx on vanilla AutoCAD and not a vertical product
AutoCAD has startup switches that allow certain things to happen while starting AutoCAD. One of those switches allows you to start AutoCAD without a vertical product. While CADWorx can run on top of vertical products like Civil 3D, Map 3D and others, you can save your resources by not loading those products when you are using CADWorx.
To change your startup switches you need to locate your CADWorx desktop shortcut. Right click and open the properties.
In the properties dialog you will find a Target field where it houses the path to the AutoCAD exe and then a list of switches. Your default CADWorx Plant Target path should like like the below path:
"C:\Program Files\Autodesk\AutoCAD 2015\acad.exe" /P CADWorx_Plant_2015
Adding the following switch should force AutoCAD to load without its vertical product: /product ACAD
You should have something like this when you are finished:
"C:\Program Files\Autodesk\AutoCAD 2015\acad.exe" /P CADWorx_Plant_2015 /product ACAD
To test this, Close CADWorx and reopen with your modified shortcut. You should now see CADWorx running without the AutoCAD vertical product.
For more information on AutoCAD startup switches please visit: http://knowledge.autodesk.com/support/autocad/troubleshooting/caas/sfdcarticles/sfdcarticles/Startup-switches-for-AutoCAD.html
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