When you try to install a critical update, rollup, hotfix, or security patch, Update.exe may use all or most of your CPU resources.
This behavior will occur if the update uses Update.exe version 22.214.171.124, which requires the Debug Programs user right (SeDebugPrivilege), AND you have revoked this right from administrators.
NOTE: SeDebugPrivilege is granted to administrators and to Local System by default.
NOTE: You can expand the update package (package.exe - x) to check the Properties of Update.exe.
To workaround this issue, either download the updated packages, or grant the Administrators group the Debug Programs user right.