This topic exactly matches that description:
https://forums.sketchup.com/t/memory-consumption-constantly-increasing-then-system-freezes/25269
In that particular case it was 3D connexion mouse related.
You could try the disabling of Ruby we talked about in this topic, to quickly tell if the problem is extension related:
https://forums.sketchup.com/t/did-the-latest-windows-update-break-sketchup/100076/27