I have a laptop that sometimes slows WAY down because of Windows 10 Real Time Protection. If you turn RTP off manually it will eventually turn itself back on.
Also I do not let the UCCNC laptop connect to the internet, I do let it connect to my personal network though. I set my router to not let the machine connect to the internet.
Here is a link that instructs you how to permanently turn real time protection off: https://learn.g2.com/how-to-turn-off-windows-defender
So far, so good. Will update if I notice any problems. It has worked for me for around a week now.