Windows 10 Creators update issues

[UtwigMU]

Usually the antimalware service is eating resources.

[VJ]

Did you look in Task Manager to see if there were any processes eating up resources? Sometimes after new installs there is a process or two that will consume resources for a while, like rebuilding search indexes and the like.

Nope, cpu usage was low.
But the system sometimes behaves like that when I have slow internet (connected to WPA2-Enterprise). And it is weird, even e.g. a command prompt can go slow: you type the characters and they appear later, one at a time... All program have a similar behaviour sometimes... So I don't think this was due to the update.