https://www.forbes.com/sites/gordonkelly/2019/09/01/microsoft-windows-10-update-problem-cpu-performance-warning-upgrade-windows-10/#7dcd007a3c85
Apparently the latest Update is causing issues of high CPU usage from Cortana.
I always update everything I can find to update on win 10, which sits on three of our machines. I haven't experienced anything like this. But that lady in the bottom left corner is usually ignored, and is given no spying 'yes' options.
I haven't experienced this but I will have to check to see if that update is installed on my system. I'll try and remember to check and report back. I use Windows 90% for gaming - the other 10% is when I don't want to bother rebooting to go back to Linux after gaming just to check my email or watch a netflix tv show.
Btw, Buster, Cortana continues running in the background regardless of how you've set it, AFAIK.
Apparently on my machine this update hasn't been installed yet. It's called the Cumulative Update for Windows 10 Version 1903 for x64-based Systems (KB4512941). I thought this had already been installed on my machine but I see there is an earlier version of this update with the same name but with a different KB number, specifically KB4512508. Note that both of these are different from the Feature update to Windows 10, version 1903.
Note that in Windows Update, troublesome updateis shown as being optional so it won't be pushed onto your system unless you choose to do so. Not sure it was initially - perhaps this is Microsoft's way of making sure you are consciously applying it because of known issues. You can still check and install other needed updates - it won't hold you back.
Now that I know some are experiencing issues, I know I'm going to be cautious. It may seem like you're being a good little user to apply all available updates right away but it can be a bad idea. Unless an update is to fix a security issue being exploited in the wild, it can be better to wait a week or two, even a month before applying Windows updates. You can do this automatically by deferring updates under advanced settings in Windows Update.
With Linux I find this kind of thing rarely ever happens so I apply all updates right away.
I did find some problems on Marilyn's win 10, but it was apparently connected to uTorrent. Symptoms included an overly used cpu. So I removed uTorrent and the problem went away. Googled and found many complaints of malware riding with the torrent program. No idea if it's true. She doesn't use it anyway. It's gone. Her system is wonderful again. Her happiness makes me happy.
The only time I would use a torrent program in Windows is to download a distro. But I can do that in virtual.
I think if you get uTorrent directly from the uTorrent site you won't have malware - it's that some other sites repackage it with malware or just spy/bloatware that makes the system slow. But it could be selection within the install.
Another alternative it to use ninite (https://ninite.com/) for installing Windows software - you pick what software you want installed (quite a few selections of free software but it's not all-inclusive) at the website and it makes a custom installer that installs them all with no interaction from you required and it installs it without any other bloatware. Fast and easy.
I'm glad your wife is happy :)
This installation of uTorrent goes back years. It did have updates regularly. Why it became a problem now is a mystery that I don't need to solve. If that Windows machine needs a torrent program, I'll probably put qBittorrent in.
Looks like Microsoft is acknowledging the problem now (https://www.forbes.com/sites/gordonkelly/2019/09/03/microsoft-windows-10-update-problem-cpu-performance-spike-warning-upgrade-windows-10/), sort of.