Snooping around "Activity Monitor" without any knowledge is guaranteed to end up badly. So you sit there and watch processes you know nothing about using ram and cpu cycles and you get all worried. Don't do that. Let the operating system do its job and manage its processes.
No, xprotect using up ram does not mean there's threat, it doesn't mean anything. Let the system deal with things. Also know that malware does not get on your system without YOU allowing it to by authorizing its installation because you fell for some too-good-to-be-true app or advertisement. Malware cannot, I repeat, cannot install itself without you allowing it. A very good way to get malware is by downloading and installing pirated software. Greed is the number one factor.