Thanks for all the suggestions, everyone! Very much appreciated.
However, the issue is till there.
The graphics driver is up to date, and the problem is definitely SketchUp itself, NOT the hardware. I just discovered that SketchUp incorrectly identifies the amount of memory on the graphics card: for some unknown reason, it seems to think that the Nvidia GeForce GTX 960M only has 1 MB of RAM! It actually has 12 GB of RAM (12237 MB, to be more precise). There’s 4 GB of video memory alone. However, the “SkecthUp Checkup” program thinks that there is only 1 MB. It reports: “Error: Your “GeForce GTX 960M/PCIe/SSE2” graphics card has 1 MB of graphics card memory. SketchUp requires a graphics card that has 256 MB or more of memory.” When I check the graphics memory reported by Windows, it correctly identifies “Total available graphics memory: 12237 MB”
I have no idea if this error with SketchUp’s inability to correctly identify graphics memory is related to the problem I’m having with the massively slow initial “Make Component” bug. I guess it might be, but I have no way of knowing.
The other issue I noticed is that the actual .skp model file grows by several megabytes each time this problem occurs. I have seen a file grow from 50 Mb to 56 Mb from just one simple operation of creating a basic cube. In other words: open the existing file, draw a rectangle, push/´pull it out to a cube, select the geometry, “Make Component”, wait nine minutes while it does that, save the file, exit SketchUp, and the file has now inexplicably grown by 6 MB. If I then open the file again and repeat the operation, it takes another 9 minutes to do that, and the file grows again, to maybe 60 Mb or so. It seems to grow by a random amount on each successive occasion, sometimes just a couple of kb, sometimes many MB. If I then purge the model, the file size does not decrease: it stays at the new, grossly inflated size forever after.
The only workaround I have found is to never close the file! Keep it open for weeks at a time, never shutting down the system, never exiting SketchUp. As long as I keep it open, it works normally after that first eternally long “Make Component”, and does not seem to have any further issues, unless I close the file and open it again. I can save the file, and even save multiple versions of the file, with no issues. The ONLY issue is the very first time I do a “make component” operation after opening a file.
So that’s where I am: the issue is definitely SketchUp, not a shadow of a doubt, and they don’t seem to be too interested in fixing it, or even admitting it. It’s not hardware, since it occurs on two entirely different computers with very different configurations. It is SketchUp itself.
Any other ideas from the experts here?