Windows update is a very useful function for OS. If your OS face any internal error and if Microsoft aware of the issue they fix the problem and publish hotfix for those issues. So windows update automatically downloads those hotfix and update OS.
But it is not necessary that each and every operating system face system error. But most of the time windows update automatically download hotfix and install it. In that case OS get overloaded sometimes and work slowly.
So, we recommended that you should disable automatic windows update unless you don’t face any internal error. If you face in critical system error and don’t know how to fix it, turn on windows update and select let me choose what to install and carefully check the update list which have downloaded and only install necessary hotfix file.
You can take expert advice in this regards.