Hi Philipy-
Welcome to SketchUp! It’s likely that you’re running into one of these issues:
The first possibility is that your machine has a particular update installed which is known to cause unreasonable slowdown in SketchUp. There’s a thread with exhaustive discussion of this topic - I wish I had a more concise description for you, but roughly speaking I believe the fix is to uninstall this particular Microsoft update.
https://forums.sketchup.com/t/selection-tool-process-is-slow-unbearably-slow
The next most likely possibility is an issue with the graphics card driver on your system. The Intel HD integrated graphics cards are known to cause problems if the graphics driver is not completely updated to the latest. You should be able to find more exact guidance if you search the forum for your exact card number (e.g. HD 4500, HD 5000, etc).
Thanks,
Marc