Svchost.exe causes 100% cpu utilization for an extended period of time after boot up or after running Windows Update or Windows Defender. If you have this problem, be sure to download this hotfix. I’ve (and ten thousand other people) seen this problem many times before. The most common symptoms are Svchst.exe saying pegged at 100% CPU utilitization after booting up and after running the latest version of Windows Defender or running Update or. running the new version of the software.”]
Source: https://www.csoonline.com/article/2633009/new-svchost-patch-for-xp-released-.html