Windows has detected performance is slow

I have never heard of Windows doing such a thing. Be very careful of what you tick on it might be an infection.
If it was my computer I would run a updated scan with my updated anti virus and a updated scan with Malwarebytes Anti Malware
Please fill in your specs completely.
Take a look at mine and it will give you a idea.
*Lower left of post

occasionally i have run a game on the wifes laptop and the color scheme has changed from aero to basic, it turns itself back on when i stop the game,
a pop up message informs you when this happens
what were you running at the time you got the message.
or do you get the message whatever you are doing.

Thanks Boohbah I learned something. Sorry about the scare (infected?), forgive me.