A number of Windows services utilize "svchost.exe", including "User Manager" and "Windows Error Reporting Service", It is probably buggy, some one can verify it comparing it an earlier release, or exchange it for a quick diagnosis. For deeper analysis, Sysinternals may be handy, but I guess we will gain nothing since it is a pre-release and Microsoft will fix it in due course.
Just a heads up, they will not stop Malware, you are talking spyware, hijackers, browser infections. Malware is everything. They will not stop most Virus's, Trojans, Worms, rootkits or probably any in the wild. Though the problem isn't Malware, just letting you know.
important: this build was going wild on CPU usage when idle. all the time no less than 47% use, clean and even after fresh install, went back to LTSB and all good here with updates and everything