Noted a few stutters of late that are fairly regular and about a minutes apart, so I suspect windows 10 may be responsible.  Firewall or virus scan?  Which ones (if any) do you keep on or switch off?  Is there a quick way to do this or can they be set to ignore msfs or my entire E drive if necessary?

If you are using windows security, you can add msfs to the exclusion list so it won't be scanned 

20 minutes ago, devgrp said:

If you are using windows security, you can add msfs to the exclusion list so it won't be scanned 

Yeah, thanks.  It's already set to ignore my entire E drive, but I still have a stutter.  May be unrelated, but will run a flight with all security settings of and see if it is any different.

The windows desktop wallpaper sideshow can cause a stutter. I have over 100 4k screenshots that change once an hour and when it changes my system stutters. You can see this when watching videos or task manager. Do you have a slideshow and how often does it change? Long shot.

You really don't want to turn off either I'm afraid. But the Firewall should not be an issue as it will recognise legitimate traffic initiated from inside your PC perimeter - MSFS for example.
Virus scan will impact especially on deep scans, but I would I move the scan to 'out of hours' if you can.

1 hour ago, Maladoror said:

The windows desktop wallpaper sideshow can cause a stutter. I have over 100 4k screenshots that change once an hour and when it changes my system stutters. You can see this when watching videos or task manager. Do you have a slideshow and how often does it change? Long shot.

Nope, just the bog standard W10 desktop for me.  I find many pictures and slideshows make the icons a bit difficult to see, so just stick to the basic - which uses minimum resources.

I have a lot of addons, so that may be the issue.  Time to empty the community folder and see what happens.  Whatever, if the odd stutter is the price I have to pay, I guess I can live with it.