If you can identify that particular update, you could try uninstalling it — rolling back your laptop to a time prior to that update. While Microsoft with Windows 10 will eventually want you to put that update back on, if it solves the stability issue it would help reveal the cause.
Another option would be to either uninstall Mozilla (Firefox) and reinstall it, or install an unrelated browser like Chrome just to see if the issue persists across other browsers. If so, it may also suggest the OS update is the culprit.
While not as visible, the old Internet Explorer should still be available. I’d also launch that and try hitting the problematic sites to see if it also behaves similarly.
I appreciate your two cents, friend, but re-read my post. I’ve already done everything you suggest.
This latest update cycle appears to be particularly heavy duty.