Slow boot times, sometimes freezes, this are some of the symptoms described by some users after installing Microsoft’s April 2019 Patch Tuesday.
As it seems this happens in machines with McAfee Endpoint Security (ENS) installed.
Both McAfee and Microsoft have identified the issue and are currently investigating the issue:
McAfee Knowledge Center - KB91465
BleepingComputer - Windows April Updates Also Have Problems with McAfee Software
