Sketchup pro / very low or crash with complex autocad 3D files

Hello
My problem is : we receive complex 3D autocad files, and when we use it on 3D Sketchup pro, the system is very low, and if we use 2 files like that, the system crashes…
Is it possible to convert 3D complex autocad files into simples and smaller files (we only have here autocad LT in 2D) before exporting them to Sketchup pro ? (we have version 2012)
The files received are complexes, we don’t need internal details but we don’t have 3D software to make it more simple… any ideas ?
Thanks

Do you have an example file?

A list of stuff to prep a CAD file…