Weird norton icon, what does it mean?

Hi guys, recently ive noticed this icon appearing when i play games on my laptop. i can only see it when i exit the game and open the toolbar quick enough. im not too sure but when my game starts to lag ( runs slower)  i open the toolbar and notice this icon, and then it disappears and it goes back to normal speed. Does anyone know  what it means or how it effects the performance of my laptop?

thanks.