I found a similar situation with a new HP ZBook Studio G4 mobile workstation running Windows 10 Pro. It has 32Gb ram, Xeon E3-1535M v6 CPU, 1Tb SSD, Intel HD Graphics P630 integrated GPU and Nvidia Quadro M1200 discrete GPU. Tried using each to learn the Nvidia M1200 is the better choice but my drawings in SketchUp Pro 2018 do often freeze (more like a stall) then recover to allow me to proceed. But everything I do (each selection/ action) seems to take forever! I have been reviewing how each of my recent drawings are ‘assembled’ which include several outside models that I imported, a base plan .jpg image, and [admittedly] some clumsy line work I take responsibility for creating. I have not been able to ‘fix’ the drawings to allow working any quicker and the average file size is close to 130Mb. One drawing, in particular, is of a 3 acre parcel conceptual site development. I haven’t introduced base contour elevations just to keep things simple - so I thought. I ran the SketchUp 2018 Checkup tool and it doesn’t seem to recognize either GPU as ‘acceptable’ since it doesn’t ‘see’ the available graphics memory.
So, with all this noted, the answer to your original question - go into the machine settings and set video graphics to ‘performance’ - to only see the AMD Radeon GPU - and then see if things improve. I had to go into my machine BIOS to disable the integrated GPU (an HP ‘thing’) but it seems to have improved the performance a bit. Good luck!!