Selection Tool process is slow, unbearably slow

OK. I had pretty much all the problems described above, and thought it would be unwise and unsafe to start uninstalling Windows Updates.
In the end, I found out what the problem was in my case.
Dell Precision Workstation, with Intel Graphics Card and also NVIDIA High performance graphics card.
I downloaded the Sketch Up Check Up tool here:
http://dl.trimble.com/sketchup/install-checkup.exe10
It recognised that when I installed the new SketchUp 2017, my NVIDIA controller stopped being activated, and it was trying to run the SU graphics through the ow grade built in Intel graphics card.
I opened the NVIDIA control panel and activated a profile or SketchUp, and voila!
All the most recent Windows Updates are installed, and SketchUp Pro 2017 runs super fast.
I hope this helps others.

The reason for this is that in the Windows Update there is a tool that lets the system assign a graphics card depending on the programme, and in my case, it was choosing the wrong one.